Immunology: Immune Responses Flashcards
Which 3 cytokines secreted by macrophages may contribute to the development of fever and sepsis?
Interleukin-1, interleukin-6, tumor necrosis factor-α
What is the definition of an anergic state?
It is an inactive state in which an immune cell cannot become activated when exposed to a specific antigen
How does Epstein-Barr virus invade B cells to cause infectious mononucleosis?
EBV binds to CD21on the surface of B cells (must be 21 to drink Beer in a Barr)
Myasthenia gravis, Graves disease, and pemphigus vulgaris are examples of what type II hypersensitivity mechanism?
Cellular dysfunction, in which the opsonized cells do not function normally but are not completely destroyed
A patient is diagnosed with a hereditary deficiency of the enzyme involved in the regeneration of NADPH from NADP+. Which enzyme is deficient?
Glucose-6-phosphate dehydrogenase (G6PD)
What steps in antibody generation are antigen independent or antigen dependent?
Generation of antibody diversity is antigen independent; generation of antibody specificity is antigen dependent
When a cell is opsonized (coated) by antibodies in a type II hypersensitivity reaction, what are the cell’s 2 potential fates?
Phagocytosis and/or complement system activation or destruction by natural killer cells (antibody-dependent cellular cytotoxicity)
Iron is an essential nutrient for microbes. What protein found in secretory fluids and neutrophils counteracts microbes via iron chelation?
Lactoferrin
What does a live attenuated vaccine contain?
A microorganism that has been modified to lose its pathogenicity (though it retains the capacity for transient growth within the host)
What lab findings are associated with hyper-IgE syndrome (Job syndrome)?
Increased IgE levels and eosinophilia
What is the pathophysiology of leukocyte adhesion deficiency type 1?
Lack of LFA-1 integrin (CD18) on phagocytes → impaired migration and chemotaxis
Type IV hypersensitivity reactions can occur by 2 mechanisms. Describe the inflammatory reaction mechanism
Effector CD4+ T cells detect antigen and release cytokines that induce inflammation
A patient experiences severe graft dysfunction within minutes of kidney transplantation. What is the correct treatment?
Removal of the graft (the appropriate treatment for a patient with hyperacute rejection, which occurs within minutes of transplantation)
The Arthus reaction is what type of hypersensitivity reaction?
Type III
How is the lectin pathway of the complement system activated?
Mannose or other sugars found on microbial surface
Name the 2 autoantibodies associated with pernicious anemia.
Antiparietal cell and anti-intrinsic factor autoantibodies
What is the main drawback associated with toxoid vaccines?
They stimulate the production of antitoxin levels that decrease with time (requiring subsequent boosters)
An hour after blood transfusion, a patient reports fever, dyspnea, flank pain, and jaundice. What is the diagnosis?
Acute hemolytic transfusion reaction (type II hypersensitivity); antibodies to donor RBC surface antigens cause extravascular hemolysis
Describe the mechanism by which type II hypersensitivity causes inflammation.
Binding of antibodies to cell surfaces leads to complement system activation and Fc receptor–mediated inflammation
A patient with IgA deficiency develops wheezing, hypotension, and respiratory arrest after receiving a blood transfusion. What is the most likely cause?
Type I hypersensitivity reaction to IgA in donor blood; patients with IgA deficiency must receive blood products that do not contain IgA
A patient with cancer appears thin with prominent temporal muscle wasting. Which cytokine is known to promote this process?
Tumor necrosis factor-α (promotes cachexia in malignancy)
Mast cells play a major role in immediate, type I hypersensitivity. Which antibody isotype facilitates this phenomenon?
IgE (cross-links when exposed to an allergen and mediates the release of inflammatory mediators)
Which type of cells produce and secrete interferons?
Virally infected cells (interferons interfere with viruses)
What are the 5 major adverse effects shared by interferons when used in pharmacotherapy?
Myopathy, neutropenia, flu-like symptoms, depression, and autoimmune reactions (interferon-induced autoimmunity)
How might a 2-month-old child receive passive immunity from her mother outside of the womb?
Via breastfeeding (breast milk contains maternal IgA)
What is the inheritance pattern for ATM gene mutations causing ataxia-telangiectasia?
Autosomal recessive
Name the 2 proteins that prevent complement activation on self cells.
Decay-accelerating factor (DAF), also known as CD55, and C1 esterase inhibitor
IgA is secreted in its dimeric form with an associated J chain. In which bodily secretions is the antibody found?
Tears, saliva, mucus, and breast milk
What test is used to assess for contact dermatitis?
Patch test
Which type of hypersensitivity is involved in transplant rejections?
Types II and IV
What are the 3 main functions of interleukin-5?
Stimulates growth and differentiation of eosinophils, promotes B-cell growth and differentiation, enhances class switching to IgA
Which type of immune cell secretes TNF-α?
Macrophages
Which antibody isotype is the most abundant in serum?
IgG
A 4-year-old girl is diagnosed with common variable immunodeficiency. What type of poliovirus vaccine may be contraindicated?
The Sabin oral vaccine (live, attenuated polio vaccines are contraindicated for patients with B-cell deficiencies)
Name the autoantibodies associated with dermatomyositis and polymyositis.
Antisynthetase (eg, anti-Jo-1), anti-SRP, and anti-helicase (anti-Mi-2)
What test is used to determine T-cell immune function, via a type IV hypersensitivity-mediated reaction?
Candida skin test
A patient presents with dark urine, a low haptoglobin level, and lysed RBCs on blood smear due to a defect in the complement system. What is the diagnosis?
Paroxysmal nocturnal hemoglobinuria
What are 2 key examples of bacterial toxoid vaccines?
Corynebacterium diphtheriae (diphtheria toxoid) and Clostridium tetani (tetanus toxoid)
Chronic granulomatous disease can be treated with which glycoprotein-based therapy?
Interferons
Rheumatoid factor, often positive in rheumatoid arthritis, is an autoantibody targeting which immunoglobulin?
It is an IgM antibody against the Fc region of IgG
What are the common causes of serum sickness-like reactions?
Drugs such as penicillin (acting as haptens) and infections such as hepatitis B
A 55-year-old patient receives a Td (tetanus and diphtheria) booster vaccine. He received all of his childhood vaccines. Why is this booster necessary?
The vaccines against Clostridium tetani and Corynebacterium diphtheriae are toxoids, which are associated with decreasing antitoxin (antibody) levels over time
What is the purpose of anergy in regulating acquired immunity?
To promote self-tolerance
When does intravascular hemolysis occur in acute hemolytic transfusion reactions?
When ABO blood group incompatibility exists
Describe the lectin pathway all the way to C5 cleaving into C5a/b.
C1-like complex cleaves C4 into C4a/C4b → C4b + C2b → C4b2b (C3 convertase) cleaves C3 into C3a/C3b → C4b2b3b (C5 convertase) cleaves C5 into C5a/C5b
Which 2 viral infections are commonly treated with interferons?
Chronic HBV and HCV infections
A patient with leukemia receives a bone marrow transplant and develops graft-versus-host disease. How is this a potentially desirable effect?
This may be beneficial in the eradication of leukemia cells (the “graft-versus-tumor” effect)
The hinge region of an antibody connects which 2 domains?
The Fab region of the heavy chain and the Fc region; specifically, CH1 and CH2 domains
Anti-glomerular basement membrane autoantibodies are associated with which disorder?
Goodpasture syndrome
A boy has thrombocytopenia, eczema, and recurrent pyogenic infections. What conditions is this patient increased risk for?
Malignancy and autoimmune diseases (he has Wiskott-Aldrich syndrome)
A woman receives a bone marrow transplant. Afterward, detection of which cell surface protein indicates a successful procedure?
CD34 (indicative of hematopoietic stem cells)
Name the disease that is implicated with defects in anchoring of complement inhibitors, such as decay-acclerating factor (DAF/CD55) and MIRL/CD59.
Paroxysmal nocturnal hemoglobinuria
Which 4 types of HPV does the standard quadrivalent subunit HPV vaccine protect against?
Types 6, 11, 16, and 18
What is a common histologic manifestation of chronic rejection of a liver transplant?
Vanishing bile duct syndrome
What is the enzyme that catalyzes the conversion of oxygen (O2) to superoxide (O2-•) in the first step of respiratory burst?
NADPH oxidase (converts O2 into O2-• via the conversion of NADPH into NADP+)
A patient has fever, joint pain, lymphadenopathy, hives, and proteinuria. He began taking a new drug 7 days ago. What is the diagnosis?
Serum sickness (type III hypersensitivity reaction)
Which antibody isotype acts as the main antibody in the secondary, delayed response to an antigen?
IgG
Which molecular cofactor is required for both the creation and neutralization of reactive oxygen species (ROS)?
NADPH
What are the 3 main functions of tumor necrosis factor-α?
Activation of endothelium, recruitment of WBCs, promotion of vascular leak
Aside from a bone marrow transplant, what other treatment measures are important for patients with severe combined immunodeficiency (SCID)?
Antimicrobial prophylaxis, administration of IVIG, and avoidance of live vaccines
A pregnant patient asks about receiving the MMR vaccine. Why would you avoid giving her this vaccine?
Because MMR is a live attenuated vaccine, the microorganism may revert to a virulent form (and is therefore contraindicated in pregnancy and immunodeficiency)
B cells undergo gene rearrangement and differentiate into plasma cells. As plasma cells, which immunoglobulin (Ig) isotypes will they be able to secrete?
IgA, IgG, or IgE
What are the 4 types of hypersensitivity reactions?
Anaphylactic and Atopic (type I), antiBody-mediated (type II), immune Complex (type III), and Delayed (type IV, cell-mediated) (ABCD)
What Ig isotype most commonly forms the immune complexes implicated in type III hypersensitivity reactions?
IgG
A patient has a rash on her cheeks, arthralgias, and antibodies to ANA and dsDNA. What type of hypersensitivity reaction causes this disease?
Type III (the patient has SLE)
Thymic aplasia results from a failure in the development of what pharyngeal pouches?
3rd and 4th pharyngeal pouches
A defect in what gene prevents anchoring of complement inhibitors in paroxysmal nocturnal hemoglobinuria?
PIGA Gene
A patient receiving treatment with IFN-α for renal cell carcinoma develops symmetric pain and stiffness of the PIP and MCP joints. What has likely occurred?
Interferon-induced autoimmunity has likely developed (manifesting similarly to rheumatoid arthritis in this case)
Describe the mechanism of the immediate phase of a type I hypersensitivity reaction.
Antigen crosslinks IgE on the surface of presensitized mast cells → immediate degranulation → release of histamine and tryptase
Which type of immune cell secretes interleukin-1?
Macrophages
IgA crosses epithelial cells by transcytosis. In which structural form is IgA secreted?
Dimeric form, with J chain (monomeric form only found in serum)
What is the classic triad of presentation seen in ataxia telangiectasia?
Ataxia, spider Angiomas, decreased IgA
A patient with fevers and a new heart murmur is found to have tricuspid endocarditis. Blood cultures grow yeasts with pseudohyphae. What immune cell count may be reduced?
Granulocytes may be deficient (increasing the risk of systemic or bloodstream candidal infections)
A patient is diagnosed with X-linked agammaglobulinemia. To what type of recurrent bacterial infection is he most susceptible?
Encapsulated (Please SHINE my SKiS: Pseudomonas, Streptococcus pneumoniae, H Influenzae type b, N meningitidis, E coli, Salmonella, Klebsiella, group B Streptococcus)
In what part of the phagocyte does respiratory (oxidative) burst occur?
The phagolysosome
What are the 2 key disadvantages of subunit vaccines?
They are expensive and induce a weaker immune response
Inactivated or killed vaccines are often safer but weaker than their live attenuated counterparts. What type of active immune response is triggered?
A humoral response only
What are the 4 main functions of interleukin-1?
Induces fever and acute inflammation, activates endothelium to express adhesion molecules, induces chemokine secretion to recruit WBCs, activates osteoclasts
What 3 immunoglobulin isotypes are typically decreased in patients with ataxia-telangiectasia?
IgA, IgG, and IgE
What response can the cytokines interleukin-1, interleukin-6, and tumor necrosis factor-α all cause?
Fever
How is a killed vaccine prepared?
The pathogen is inactivated with heat or chemicals before administration (leaving the epitope structure on surface antigens intact)
Which class of medication is contraindicated for patients with C1 esterase inhibitor deficiency?
ACE inhibitors because they also increase bradykinin levels
Combined active and passive immunization should be given when exposure to what 2 diseases is suspected?
Hepatitis B virus, rabies virus
A patient presents with swelling and pain in her PIP and MCP joints, bilaterally. Of the autoantibodies associated with this condition, which are more specific?
Anti-CCP autoantibodies (this is rheumatoid arthritis)
What 2 stimuli are required for NK cells and T cells to secrete interferon-γ?
Exposure to antigens, exposure to interleukin-12 from macrophages
What are 10 key examples of live vaccines?
Adenovirus/Typhoid/Polio/Varicella/Smallpox/BCG/Yellow fever/Influenza/MMR/Rotavirus (Attention Teachers! Please Vaccinate Small, Beautiful Young Infants with MMR Regularly) was
A patient agrees to receive the annual injected influenza vaccine. What is the main drawback of this type of vaccination?
Because it is an inactivated vaccine, the immune response is weaker (booster shots or repeated vaccinations are often required)
Name the 2 complexes that can act as C5 convertase in the complement system.
C3bBb3b (from alternative pathway) and C4b2b3b (from classical/ lectin pathway); both act to cleave C5 into C5a and C5b
Which immunodeficiency syndrome is commonly treated with interferons?
Chronic granulomatous disease (CGD)
What is the most common cause of hyper-IgM syndrome?
Defective CD40L on T helper (Th) cells, which is necessary for B-cell class switching
What is the main advantage associated with the administration of a live attenuated vaccine?
Strong, often lifelong immunity is produced
In the generation of antibody diversity, nucleotides are added randomly to DNA during recombination. What enzyme performs this action?
Terminal deoxynucleotidyl transferase (TdT)
An immunoglobulin is released in breast milk and does not fix complement. Name this immunoglobulin isotype.
IgA
What is serum sickness?
An immune complex disease; antibodies to foreign proteins are made and deposited in tissues, where they fix complement and cause damage
What autoantibodies are associated with diffuse scleroderma?
Anti-Scl-70 (anti-DNA topoisomerase I [Scleroderma])
The bacterial catalase enzyme converts H2O2 generated from oxidative burst into what 2 products?
Water, oxygen
What is the mechanism of the hypersensitivity reaction involved in polyarteritis nodosa?
In type III hypersensitivity, antigen-antibody complexes activate complement, leading to neutrophil chemotaxis and immune complex deposition
What is the genetic inheritance of IL-12 receptor deficiency?
Autosomal recessive
A boy has recurrent Staphylococcus aureus, Escherichia coli, and Aspergillus infections. Which 2 tests confirm the diagnosis?
Negative nitroblue tetrazolium and abnormal (↓ green fluorescence) dihydrorhodamine test results (diagnosis: chronic granulomatous disease)
Which disease is associated with antimitochondrial autoantibodies?
Primary biliary cholangitis
MPO-ANCA/p-ANCA autoantibodies are associated with which 3 disorders?
Microscopic polyangiitis, Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis), and ulcerative colitis
Patients with ataxia-telangiectasia are at increased risk for which malignancies?
Lymphomas and leukemias
Patients with DiGeorge syndrome are susceptible to what type of infections?
Viral and fungal (due to absence of T cells)
A patient with pancytopenia who is undergoing marrow chemoablation in preparation for bone marrow transplantation requires blood products. What must be done before transfusion?
The blood products must be irradiated (as this helps prevent GVHD in immunocompromised patients)
How does the humoral type of acute rejection differ from hyperacute rejection in its pathophysiology?
Antibodies against graft donor antigen(s) develop after transplantation in acute rejection (vs pre-existing antibodies in hyperacute rejection)
What characteristic findings are seen in chronic mucocutaneous candidiasis?
Lack of cutaneous reaction to Candida antigens and absence of in vitro T-cell proliferation in response to Candida antigens
What medical measure is contraindicated in patients with X-linked (Bruton) agammaglobulinemia?
Live vaccines
A new mother expresses concern that her baby will have a “bad reaction” to the Hib (Haemophilus influenzae type b) vaccine. What is the correct response?
The chance of an adverse reaction to a subunit vaccine (eg, Hib) is extremely low, even relative to other vaccine types
Besides typical T-cell surface proteins (TCR, CD3, CD28), which cell surface proteins do regulatory T cells have?
CD4 and CD25
Membrane attack complex (MAC) is important for protection against what type of organisms?
Gram-negative bacteria
Why are patients with chronic granulomatous disease (CGD) susceptible to catalase-positive organisms?
Catalase-positive species can neutralize their own H2O2, leaving the phagocytes of patients with CGD incapable of producing ROS
The interferon response is classified as a component of what branch of the immune system?
The innate response
What is the temporal onset and duration of passive immunity?
Rapid onset but short duration of antibody protection (half-life of 3 wk)
Which HBV antigen does the recombinant subunit HBV vaccine contain?
HBsAg (which is why vaccinated patients are typically positive for the anti-HBs antibody)
What are the 3 mechanisms of a type II hypersensitivity reaction?
Opsonization/phagocytosis, complement- and Fc receptor–mediated inflammation, antibody-mediated cell dysfunction
To what specific region(s) of the heavy chain do macrophages bind?
CH2 and CH3 regions
What conditions might be seen in patients with common variable immunodeficiency?
Autoimmune diseases, bronchiectasis, lymphoma, sinopulmonary infections
Anti-U1 RNP (ribonucleoprotein) autoantibodies are associated with which disorder?
Mixed connective tissue disease
Name the 3 autoantibodies associated with celiac disease.
IgA and IgG deamidated gliadin peptide, IgA anti-endomysial, IgA anti-tissue transglutaminase autoantibodies
Which disorder is associated with autoantibodies against the presynaptic voltage-gated calcium channel?
Lambert-Eaton myasthenic syndrome
What effect can a T-cell deficiency have on a bacterial infection?
Increased risk of sepsis (due to rapid dissemination of the infection)
How rapidly does chronic transplant rejection develop?
Within months to years of transplantation
The umbilical cord fails to separate within 30 days in a neonate. Neutrophilia is noted on labs. What is the diagnosis?
Leukocyte adhesion deficiency type 1
Describe the mechanism of serum sickness.
Antibodies to foreign proteins are produced; 1–2 wk later, antibody-antigen complexes are formed and deposited in tissue → complement activation → inflammation/tissue damage
After exposure to which 6 agents may preformed antibodies be administered (as a part of postexposure prophylaxis)?
Tetanus toxin, Botulinum toxin, HBV, Varicella, Rabies virus, or Diphtheria toxin (“To Be Healed Very Rapidly before Dying”)
Anti-dsDNA and anti-Smith autoantibodies are associated with which disorder?
Systemic lupus erythematosus
What triad of symptoms are seen in Wiskott-Aldrich?
Wiskott-Aldrich: Thrombocytopenia, Eczema, Recurrent (pyogenic) infections (WATER)
A patient receiving induction chemotherapy for acute leukemia has severe granulocytopenia. To what types of microbes is she most susceptible
Bacteria (Some Bacteria Produce No Serious granules: Staphylococcus, Burkholderia, Pseudomonas, Nocardia, Serratia) and fungi (systemic Candida, Aspergillus, Mucor)
The phagocytes of patients with chronic granulomatous disease (CGD) can still make ROS from what compound provided by invading organisms?
H2O2 (however, catalase-positive organisms can neutralize their own H2O2, thus circumventing this mechanism)
How is the classic pathway activated?
By IgG or IgM mediated antigen-antibody complexes (GM makes classic cars)
What enzyme is responsible for the incorporation of chloride into hydrogen peroxide to form hypochlorite radicals?
Myeloperoxidase
Which cell surface receptors does the human immunodeficiency virus use to infect its target host cells?
HIV binds to CD4 and either CXCR4 or CCR5, which serve as co-receptors, on T helper cells
What is the general difference between infections commonly associated with T-cell and B-cell deficiencies?
T-cell deficiencies tend to produce recurrent viral/fungal infections, while B-cell deficiencies tend to produce recurrent bacterial infections
Why do cells like neutrophils and monocytes have high concentrations of NADPH oxidase?
To aid in the immune response by rapidly releasing reactive oxygen species (ROS) that kill bacteria
A patient develops hives, tongue swelling, and difficulty breathing after eating peanuts. Which complement proteins are responsible for these symptoms?
C3a, C4a, C5a—anaphylaxis
What general type of vaccine includes only the antigens that best elicit an immune response?
Subunit vaccines
Why are thymus-independent antigens weakly immunogenic or entirely nonimmunogenic?
They lack a peptide component; therefore MHC-mediated presentation to T cells cannot occur
How can acute transplant rejection be prevented or reversed?
With the use of immunosuppressants
Describe the levels of immunoglobulins that characterize selective IgA deficiency.
Decreased IgA level with normal IgG and IgM levels
How is the alternative pathway of the complement system activated?
By microbial surface molecules and spontaneously
What radiographic finding is associated with DiGeorge syndrome?
Lack of thymic shadow on chest x-ray
What is unique about the type IV hypersensitivity reaction as compared with the other types?
The response is delayed and it does not involve antibodies
A patient with HIV infection has a CD4 count of 600 cells/mm3. What are the 2 live attenuated vaccines that can be given to this patient?
MMR and varicella vaccines can be given to HIV+ patients with a CD4 cell count ≥ 200 cells/mm3
What are the 2 primary functions of C3b?
Opsonization and clearance of immune complexes
Which immunodeficiency is due to a defect in B-cell differentiation resulting in decreased plasma cell levels?
Common variable immunodeficiency (CVID)
Live attenuated vaccines often induce strong, lifelong immunity. What 2 types of active immune responses are triggered?
Cellular and humoral responses
A newborn with B+ blood born to an O+ mother develops jaundice and hepatomegaly 24 hr after birth. What is the mechanism of the disease?
Type II hypersensitivity reaction (the infant has hemolytic disease of the newborn)
Years after a kidney transplant, a patient develops chronic graft glomerulopathy. What is the mechanism of this rejection?
CD4+ T cells and antibodies react against donor antigens, including allogeneic MHCs (as this is a kidney-specific form of chronic rejection)
What enzyme catalyzes the conversion of superoxide into hydrogen peroxide in the second step of respiratory burst?
Superoxide dismutase (converts superoxide into hydrogen peroxide, H2O2)
What cardiac defects are typically associated with DiGeorge syndrome?
Conotruncal abnormalities (tetralogy of Fallot, truncus arterious, etc)
A 5-year-old boy has history of recurrent viral illnesses, truncus arteriosus, and tetany. What genetic defect is the cause of the condition?
22q11 microdeletion (he has DiGeorge syndrome)
What benefit is conferred by IgM assuming a pentameric configuration?
Increased ability to trap free antigens out of tissue while the humoral response is evolving
What is the most common primary immunodeficiency?
Selective IgA deficiency
What are 6 key examples of subunit vaccines?
HBV (antigen is HBsAg), HPV (types 6, 11, 16, 18), acellular pertussis (aP), Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b
A transplant recipient has a maculopapular rash, jaundice, hepatosplenomegaly, and diarrhea. She probably received 1 of which 2 types of transplants?
Bone marrow or liver (lymphocyte-rich tissues, which may predispose to graft-versus-host disease)
What are 2 cells that utilize the phagocyte NADPH oxidase complex?
Neutrophils, monocytes
How does IgA protect itself from breakdown by luminal proteases?
It picks up a secretory component from epithelial cells, thereby shielding its Fc portion from proteases
What unique chemical bond is found within the hinge region of an antibody molecule?
Disulfide (S-S) bond
What general type of vaccine is composed of a denatured bacterial toxin with an intact receptor binding site?
Toxoid vaccines
What types of infections are commonly seen in X-linked (Bruton) agammaglobulinemia?
Recurrent bacterial and enteroviral infections
What autoantibodies are associated with limited scleroderma/CREST syndrome?
Anticentromere antibodies
What are the 2 main functions of interleukin-6?
Induces fever and stimulates production of acute-phase proteins
What cytokine from Th2 cells enhances class switching to IgE and IgG?
Interleukin-4
What 2 cytokines are secreted by all T cells?
Interleukin-2 and interleukin-3
Which complement disorder causes recurrent Neisseria bacteremia?
Terminal complement (C5–C9) deficiencies
A CXR obtained from a patient with hypoxemia has a diffuse ground-glass appearance. This patient is likely to have a deficiency of what type of immune cell?
T cells (this is Pneumocystis jiroveci pneumonia, or PCP, a fungal infection common in T-cell–immunodeficient states)
Which 3 cell surface proteins are common to all T cells?
TCR, CD3, and CD28
What are 5 key examples of inactivated or killed vaccines?
Rabies, Influenza (injected), Polio (SalK = Killed), hepatitis A, typhoid (Vi polysaccharide, intramuscular) (RIP Always)
Which form of glutathione must be readily available in the cell to remove reactive oxygen species to prevent cell lysis?
The reduced form (GSH); recall that reducing equivalents are created in the HMP shunt
After a camping trip, a patient presents with an itchy, red, oozing rash on the lower extremities, sparing the area under his socks. What is the diagnosis?
Contact dermatitis (type IV hypersensitivity): sensitized T cells encounter antigen and release cytokines, causing macrophage activation
What are the 4 main functions of interferon-γ?
Triggers macrophages to kill phagocytosed pathogens, induces NK cells to kill virus-infected cells, increases MHC expression by all cells, inhibits differentiation of Th2 cells
What are the 3 main functions of interleukin-10?
Attenuates inflammation, decreases MHC class II and Th1 cytokine expression, inhibits active macrophages/dendritic cells (APCs)
A booster shot for the pneumococcal vaccine, PPSV23, is recommended for patients over 65. Does the antigen have a peptide component?
No; the vaccine contains a thymus-independent antigen, which lacks a peptide component
Name 4 inherited immunodeficiencies that X-linked recessive, and thus are more common in boys.
Hyper-IgM syndrome, Wiskott-Aldrich syndrome, chronic granulomatous disease, Bruton agammaglobulinemia (and some types of severe combined immunodeficiency)
Which type of immune cell secretes interleukin-12?
Macrophages
Which disease is associated with anti-hemidesmosome autoantibodies?
Bullous pemphigoid
What component on the bacterial surface does C3b bind to in order to opsonize the pathogen?
Lipopolysaccharides
DiGeorge syndrome, IL-12 receptor deficiency, Job syndrome, and chronic mucocutaneous candidiasis feature dysfunction of which cell type?
T Cells
What can be observed on flow cytometry and lymph node biopsy from a patient with severe combined immunodeficiency?
Lack of T cells on flow cytometry and no germinal centers in lymph nodes
A man comes to the clinic with a disseminated mycobacterial infection after receiving the BCG vaccine. He has low IFN-γ levels. Which leukocytes are affected in this patient?
Th1 cells (he has IL-12 receptor deficiency)
Name the organ responsible for synthesis of complement proteins.
Liver
A child develops fever, headache, flushing, and chills 4 hours after receiving a blood transfusion. How could this be prevented in the future?
By using leukoreduced blood products (this is febrile nonhemolytic transfusion reaction)
What mechanism within the oxidative burst process triggers the release of lysosomal enzymes?
K+ influx, which is triggered by oxidative burst
Starting with C1, trace the classic complement pathway all the way to the cleavage of C5 to C5a/b.
C1 cleaves C2 into C2a/C2b → C2b + C4b → C4b2b (C3 convertase) cleaves C3 into C3a/C3b → C4b2b3b (C5 convertase) cleaves C5 into C5a/C5b
Each B cell produces an immunoglobulin specific to 1 antigen. How is antibody diversity established?
1) Random recombination of VJ and V(D)J genes; 2) insertion of random nucleotides into DNA by TdT; 3) random combination of light and heavy chains
What is the pathogenetic mechanism whereby hyperacute rejection develops?
Pre-existing recipient antibodies react to donor antigens (type II hypersensitivity), causing thrombosis of graft vessels and necrosis
Which antibody isotype has the lowest serum concentrations?
IgE
Which receptor found on natural killer cells binds to the Fc region of IgG?
CD16
One mechanism of febrile nonhemolytic transfusion reactions is a type II hypersensitivity reaction. What is the other mechanism?
Cytokines that are created and accumulate in the storage of blood products can also incite the transfusion reaction
A woman has ataxia, weblike angiomas, low IgA levels, high AFP, and cerebellar atrophy on imaging. Which gene is defective?
The ATM gene: ataxia-telangiectasia is due to ATM gene defects encoding DNA repair enzymes
A patient with longstanding severe rheumatoid arthritis is diagnosed with osteoporosis. Which cytokine may have mediated the development of this condition?
IL-1, which may have been upregulated by chronic inflammation; IL-1 causes activation of osteoclasts, which can increase bone resorption
A young child has no B cells in peripheral blood, low immunoglobulins, and scanty tonsils. What is the diagnosis?
X-linked (Bruton) agammaglobulinemia
What is the pathogenesis of chronic granulomatous disease?
Defective NADPH oxidase → ↓ ROS and oxidative burst → ↑ susceptibility to catalase ⊕ organisms
A patient is diagnosed with C9 complement deficiency. Which vaccine must be given immediately?
The meningococcal vaccine to Neisseria meningitidis, as there is no formation of membrane attack complex in late complement deficiencies
What gene is affected in patients with Wiskott-Aldrich syndrome?
WAS gene
What are the 2 possible causes of severe combined immunodeficiency (SCID) and their respective modes of inheritance?
Adenosine deaminase deficiency (autosomal recessive) and defective IL-2R gamma chain (X-linked recessive)
Which cell surface proteins are found on macrophages?
CD14, CD40, CCR5, MHC II, B7 (CD80/86), and receptors for Fc and C3b
A young patient is found to have an absence of B cells. To which types of viruses is he most susceptible?
Enteroviruses including poliovirus (especially manifesting as enteroviral encephalitis)
IgM can be found as a monomeric surface receptor on B cells. In which structural form is it secreted?
Pentameric form, with associated J chains
What cell surface protein found on macrophages acts as a receptor for PAMPs, such as LPS?
CD14
Which 2 cell surface proteins are suggestive of NK cell lineage?
CD16 and CD56
Why does X-linked (Bruton) agammaglobulinemia usually manifest after the age of 6 months?
Maternal-derived IgG protects the infant against infections; those levels begin to wane at 6 months after birth
Thymus-dependent antigens are often strongly immunogenic as they contain a peptide component. Which 2 immunologic phenomena do they cause?
Class switching and immunologic memory formation due to interaction of B cells and Th cells
How do the Fab and Fc regions determine the type of antibody that will be produced?
Fab determines the idiotype (a binding pocket specific to antigen); Fc determines the isotype (IgM, IgA, etc)
Which immunoglobulin isotype is produced in the primary, immediate response to an antigen?
IgM
Individuals with selective IgA deficiency have an increased risk for infection by what specific pathogen?
Giardia species
Name the 2 molecules that act as opsonins to defend against bacterial infections.
C3b and IgG
A patient has recurrent fungal infections of the skin and mucous membranes due to a defect in the AIRE gene. Name the disease.
Chronic mucocutaneous candidiasis
A patient with sepsis is found to have elevated levels of ferritin, fibrinogen, and C-reactive protein. Which cytokine may account for this finding?
Interleukin-6 (which stimulates the production of acute-phase proteins)
Describe the mechanism by which type II hypersensitivity causes cellular dysfunction.
Binding of antibodies to cell surface receptors leads to abnormal blockade or activation of downstream processes
A child develops wheezing and hives after consuming peanuts. How would you test for the responsible hypersensitivity reaction?
Use a skin test or blood test (ELISA) for allergen-specific IgE in a type I hypersensitivity reaction
Patients with chronic granulomatous disease (CGD) experience recurrent infections with catalase-positive organisms. What enzyme is deficient?
NADPH oxidase (for example, Staphylococcus aureus and Aspergillus are common catalase-positive species seen in patients with CGD)
A boy develops hives when he eats a peanut butter sandwich. The activation of which 2 cell types is most likely to blame?
Mast cells and basophils due to IgE activation and cross-linking
Interferons are effective in the immune response to which pathogen: bacteria, virus, fungus, or parasite?
Viruses (both RNA and DNA)
What 5 types of neoplasms may be treated with interferons?
Renal cell carcinoma, malignant melanoma, Kaposi sarcoma, hairy cell leukemia, condyloma acuminatum
Which general type of vaccine is contraindicated in pregnant patients or patients with immunodeficiencies?
Live attenuated vaccines
What are the 3 main functions of interleukin-4?
Interleukin 4 induces T-cell differentiation into Th (helper) 2 cells, promotes B-cell growth, enhances class switching to IgE and IgG (ain’t too proud 2 BEG 4 help)
Anaphylaxis (eg, bee sting, some food/drug allergies) is what type of hypersensitivity reaction?
Type I
What is the main function of interleukin-3?
Supports growth and differentiation of stem cells in the bone marrow; functions like GM-CSF
What is the T-cell in vitro response to Candida antigens in patients with chronic mucocutaneous candidiasis?
Lack of T-cell proliferation
A patient develops hives, fever, and shock within minutes of receiving blood transfusion. What is the pathogenesis behind this transfusion reaction?
Type I hypersensitivity reaction against plasma proteins in the transfused blood (this is an allergic/anaphylactic reaction)
What are the 4 domains that comprise the Fab region of an antibody?
Variable light region (VL), constant light region (CL), variable heavy region (VH), constant heavy 1 region (CH1)
In what situation do T and B cells become anergic?
T and B cells become nonreactive when they do not receive a costimulatory signal (signal 2) on exposure to an antigen
Which type of immune cell secretes interleukin-6?
Macrophages
Each B cell produces an immunoglobulin specific to 1 antigen. How is antibody specificity established?
1) Somatic hypermutation and affinity maturation for the variable region (Fab); 2) isotype switching for the constant region (Fc)
Interferons can prime local cells for self-defense against viruses by inducing upregulation of what process?
MHC expression, so as to facilitate recognition of infected cells
A patient has thymic aplasia in the setting of DiGeorge syndrome. For what 5 types of viral infections is he at risk?
CMV, EBV, JCV, VZV, and chronic GI/respiratory viruses
Despite having low serum concentrations, IgA is the most abundantly produced antibody. Where is it made?
The gastrointestinal tract (by Peyer patches); it is released into secretions (tears, saliva, mucus)
Although most individuals with IgA deficiency have no symptoms, what symptoms can be present that allow for diagnosis?
Airway and GI infections, Autoimmune disease, Atopy, and Anaphylaxis to IgA-containing products
Name the gene affected in Bruton agammaglobulinemia.
BTK, which encodes for Bruton tyrosine kinase
How soon after exposure to an antigen does the immediate phase of a type I hypersensitivity reaction occur?
Minutes after antigen exposure
Which complement protein combines with C6–C9 to form the membrane attack complex (MAC)?
C5b
What is the means of acquisition of passive immunity?
Transfer of preformed antibodies
Which immunoglobulin isotype protects mucous membranes from invading pathogens?
IgA
Which antibody regions contain the variable/hypervariable regions and the constant region?
Fab contains the variable/hypervariable regions, and a small constant region; Fc contains the constant regions only
Unlike other immunoglobulin (Ig) isotypes, the function of IgD is unclear. Where can immunoglobulin D be found?
Surface of many B cells and in serum
A boy has coarse facies, retained baby teeth, and recurrent abscesses. Labs show ↑ IgE and ↑ eosinophils. Which immune cells are impaired?
Th17 cells (he has hyper-IgE syndrome [Job syndrome])
Which cell surface proteins are common to all B cells?
Immunoglobulin (Ig), CD19, CD20, CD21, CD40, MHC II, B7
For which malignancies can interferons be used as a form of therapy?
Hairy cell leukemia, renal cell carcinoma, malignant melanoma, Kaposi sarcoma
A patient has a parasite infection. In a tissue biopsy, eosinophils are seen attacking the parasites due to signaling by which immunoglobulin?
IgE
A neonate breastfeeds for the first time, receiving abundant maternal IgA in colostrum. How long is this type of immune protection likely to last?
No more than 3 wk (the half-life of an antibody), as this is a form of passive immunity
A kidney transplant recipient experiences gradual oliguria. Biopsy reveals vasculitis of graft vessels with a lymphocytic cellular infiltrate. What type of rejection is present?
Acute rejection
A previously healthy woman, not taking any medications, develops dry eyes and dry mouth. What autoantibodies can cause this?
Anti-Ro/SSA and anti-La/SSB autoantibodies, often positive in Sjögren syndrome
What are the 4 Cs to remember about the Fc fragment of an antibody?
Constant region, Carboxy terminal, Complement binding, Carbohydrate side chains
Which receptors found on macrophages enhance their phagocytic activity?
Fc and C3b receptors
What are the manifestations of velocardiofacial syndrome?
Facial and palate defects and cardiac anomalies
Antibodies are made up of heavy and light chains. Which chains contribute to the Fab and Fc regions?
Light chains contribute to Fab region only; heavy chains contribute to both Fab and Fc regions
Antibodies are made up of the Fab and Fc regions. What is the function of each region in immunity?
Fab region recognizes antigen (Fragment, antigen binding); Fc region fixes complement for IgM and IgG isotypes
A 30-year-old woman has bulging eyes, palpitations, diarrhea, and thyromegaly. What autoantibodies cause this condition?
Anti-TSH receptor autoantibodies (she has Graves disease)
A child has recurrent bacterial skin infections with absence of pus and impaired wound healing. What findings might confirm the diagnosis?
Increased serum neutrophil levels but lack of neutrophils at infection sites (this is type 1 leukocyte adhesion deficiency)
Patients with hyper-IgM syndrome are more susceptible to infection by which opportunistic organisms?
CMV, Cryptosporidium, Pneumocystis,
What autoantibodies are present in pemphigus vulgaris?
Anti-desmosome (anti-desmoglein) autoantibodies
Mature, naive B cells express what immunoglobulin (Ig) isotypes on their surfaces before class switching?
IgM and IgD
What are the 3 major types of interferons?
IFN-α, IFN-β, IFN-γ
A pneumococcal vaccine PCV13 is recommended for infants and young children. Does the antigen contain a peptide component?
Yes; the vaccine contains a thymus-dependent antigen, which contains a protein component
What are the characteristic lab findings in Wiskott-Aldrich syndrome?
Normal/decreased IgG and IgM, elevated IgE and IgA, thrombocytopenia with microsized platelets
A patient receives the oral Sabin polio vaccine. Is there a risk of the vaccine producing poliovirus infection in this patient?
Yes, but a very small one (as the Sabin vaccine is a live attenuated vaccine, which may revert to a virulent form)
What are the 2 mechanisms whereby interferons aid in the immune response against viral infection?
Upregulation of MHC expression (improving immune recognition of infected cells) and downregulation of protein synthesis (blocking viral replication)
Trace the alternative pathway from C3 all the way to the cleavage of C5.
C3 is cleaved into C3b → C3b + Bb → C3bBb (C3 convertase) + C3b → C3bBb3b (C5 convertase) cleaves C5 into C5a/b
A young boy has failure to thrive due to recurrent infections with various pathogens and chronic diarrhea. Thymic shadow is not seen on chest x-ray. Curative treatment?
Bone marrow transplant, for which graft rejection is not a concern (he has severe combined immunodeficiency)
What is a specific pathologic manifestation of chronic rejection in a transplanted lung?
Bronchiolitis obliterans
What is the name for the specific piece of the antigen to which an antibody binds?
Epitope
A boy has defective NADPH oxidase; his neutrophils produce fewer ROS. Which organism(s) is he most susceptible to?
Catalase-positive organisms (diagnosis: chronic granulomatous disease)
What autoantibodies are associated with granulomatosis with polyangiitis (Wegener)?
PR3-ANCA (c-ANCA)
Which 2 types of immune cells secrete interferon-γ?
Th1 cells and NK cells
List 4 main functions of IgG.
Fixation of complement, opsonization of bacteria, neutralization of bacterial toxins and viruses, provision of passive immunity to infants via placenta
What live viral vaccine is nonattenuated and only given to military recruits?
Adenovirus
How soon after exposure to an antigen does the late phase of a type I hypersensitivity reaction occur?
Hours after antigen exposure
What type of infections are seen in patients with common variable immunodeficiency?
Sinopulmonary infections
What are the 2 main functions of interleukin-12?
Activates natural killer cells, induces differentiation of T cells to Th1 cells
Bruton agammaglobulinemia, selective IgA deficiency, and common variable immunodeficiency are disorders of which type of leukocyte?
B Cells
Name the defective gene in Chédiak-Higashi syndrome.
Lysosomal trafficking regulator gene (LYST)
A child with an inherited immune disorder has greasy, foul-smelling stools. What type of immunodeficiency is likely?
B-cell deficiency with no IgA (giardiasis), leading to lack of mucosal immunity
A developing fetus receives passive immunity from his mother in utero. What subtype of immunoglobulin is transferred across the placenta?
IgG
Name 5 examples of type III hypersensitivity reactions.
Serum sickness, Arthus reaction, systemic lupus erythematosus, polyarteritis nodosa, poststreptococcal glomerulonephritis
Which cell surface protein is unique to cytotoxic T cells?
CD8
Describe the mechanism of the late phase of a type I hypersensitivity reaction.
After mast cell degranulation, chemokines attract inflammatory cells and other mediators from mast cells, leading to inflammation and tissue damage
For which autoimmune condition are interferons particularly effective?
Multiple sclerosis
Graft-versus-host disease is what type of hypersensitivity reaction?
Type IV
What are the 3 methods by which one can acquire active immunity to an antigen?
Natural infection, toxoid exposure, vaccination
For which infections can interferons be used as a form of therapy?
Chronic HBV and HCV, condyloma acuminatum
Which cytokine from Th2 cells enhances class switching to IgA?
Interleukin-5
Which type of immune cell secretes interleukin-8?
Macrophages
What is the mechanism of injury in transfusion-related acute lung injury?
It is due to donor anti-leukocyte antibodies attacking the recipient’s neutrophils and pulmonary endothelial cells
Interferons are what specific type of macromolecule?
Glycoproteins
To what specific region(s) of the heavy chain does complement bind?
CH2 region
A pale, blond patient has recurrent pyogenic infections, lymphohistiocytosis, and neuropathy. Pancytopenia is noted. What cellular process is affected in this condition?
Microtubule dysfunction impairing phagosome-lysosome fusion (this is Chédiak-Higashi syndrome)
What antibodies are associated with autoimmune hepatitis type 1?
Anti-smooth muscle autoantibodies
What is a specific pathologic manifestation of chronic rejection in a transplanted kidney?
Chronic graft nephropathy
Describe the difference between a direct and an indirect Coombs test.
Direct: detects antibodies that are already bound to RBCs; indirect: detects free serum antibodies that can bind to RBCs
A 2-year-old child with recurrent severe pyogenic bacterial infections has high IgM levels and low levels of all other immunoglobulins. What is the diagnosis?
Hyper-IgM syndrome
Name the 3 autoantibodies associated with Hashimoto thyroiditis.
Antimicrosomal, antithyroglobulin, and antithyroid peroxidase autoantibodies
Which 2 types of immune cells secrete interleukin-10?
Th2 cells and regulatory T cells
Which complement proteins combine to form the membrane attack complex (MAC) to mediate cytolysis?
C5b, C6, C7, C8, and C9
What is the temporal onset and duration of active immunity?
Slow onset but long-lasting immune protection (memory)
What are the 4 T’s associated with type IV hypersensitivity reactions?
T cells, Transplant rejections, TB skin tests, and Touching (contact dermatitis)
What is a specific pathologic manifestation of chronic rejection in a transplanted heart?
Accelerated atherosclerosis
Anti-phospholipase A2 receptor autoantibodies are associated with which disorder?
Primary membranous nephropathy
What are the 5 manifestations of Chédiak-Higashi syndrome?
PLAIN: Progressive neurodegeneration, Lymphohistiocytosis, Albinism (partial), recurrent pyogenic Infections, and peripheral Neuropathy
Which immunoglobulin (Ig), passed from mother to infant, is responsible for passive immunity after birth? How long does it last?
IgG, which can cross the placenta; passive immunity starts to wane after 6 mo
What 2 organs are typically absent in DiGeorge syndrome?
Thymus and parathyroid glands
What is the main function of interleukin-2?
Stimulates growth of helper T cells, cytotoxic T cells, regulatory T cells, and natural killer cells
Which complement protein attracts neutrophils to the site of infection?
C5a
Type IV hypersensitivity reactions can occur by 2 mechanisms. Describe the direct cell cytotoxicity mechanism.
Target cells are killed by CD8+ cytotoxic T cells
A mother is Rh- and her fetus may be Rh+. Which Coombs test should each of them receive?
Test mother blood for Rh+ antibodies with indirect Coombs test; test fetal blood for antibodies adhered to RBCs with direct Coombs test
A patient has recurrent infections with encapsulated organisms. His B-cell counts are normal. What other defect may be to blame?
Early complement deficiency
What is the pathogenetic mechanism whereby acute cellular rejection develops?
CD8+ T cells and/or CD4+ T cells are activated against foreign (donor) MHCs in a type IV hypersensitivity reaction
All immunoglobulin isotypes can exist in which structural form: monomers or polymers?
Monomers
What is the mechanism of complement-mediated hemolysis in paroxysmal nocturnal hemoglobinuria?
Lack of GPI anchors needed for binding of complement inhibitors (eg, decay-acclerating factor) results in complement-mediated intravascular hemolysis → ↓ haptoglobin → dark urine
A patient with odynophagia and thrush is likely to have a deficiency of what type of immune cell?
T cells, as this patient has a (local) Candida esophagitis causing painful swallowing (by contrast, systemic infections occur in patients with granulocyte deficiencies)
What type of hypersensitivity reaction is involved in graft-versus-host disease (GvHD)?
Type IV hypersensitivity
A 6-year-old girl with nausea, vomiting, urinary frequency, and sudden weight loss has a blood glucose level of 800 mg/dL. What autoantibodies should be ordered on labs?
Anti-glutamic acid decarboxylase and islet cell cytoplasmic autoantibodies (to check for type 1 diabetes)
The NK and Th1 cells within a virus-infected host are stimulated by interleukin-12. Which cytokine will be secreted by these cells in response?
Interferon-γ
Which typhoid vaccine is capable of producing a stronger immune response?
The Ty21a typhoid vaccine, which is a live attenuated (and therefore stronger) vaccine
A patient with no recorded medical history presents with angioedema. His father also had similar episodes. What is the pathophysiology of the disease?
Unregulated activation of kallikrein leading to ↑ bradykinin levels (this is hereditary angioedema due to C1 esterase inhibitor deficiency)
Interferons can prime local cells for self-defense against viruses by inducing downregulation of what process?
Protein synthesis, so as to resist potential viral replication
A patient with bronchiectasis produces blue-green sputum when she coughs. Which enzyme in neutrophils gives the sputum its color?
Myeloperoxidase, which contains a blue-green, heme-containing pigment
Reaction to PPD (a test for Mycobacterium tuberculosis) is what type of hypersensitivity reaction?
Type IV
When do cells generally synthesize interferons?
When infected by viruses (interferons interfere with both DNA and RNA viruses)
Describe the mechanism common to all type II hypersensitivity reactions.
Antibodies bind to cell surface antigens, leading to cellular destruction, cellular dysfunction, and inflammation
What pathogenetic mechanism drives the development of graft-versus-host disease?
Grafted immunocompetent T cells proliferate in the immunocompromised host and reject cells with foreign proteins, causing severe organ dysfunction
What is the means of acquisition of active immunity?
Exposure to foreign antigens
Which type of influenza vaccine is theoretically safer for most patients to receive?
The injected influenza vaccine, which is killed/inactivated (unlike the intranasal influenza vaccine, which is live attenuated)
What is another name for interleukin-1?
Osteoclast-activating factor
How rapidly does acute (cellular or humoral) transplant rejection develop?
Within weeks to months of transplantation
Describe the mechanism of a type III hypersensitivity reaction.
Anitigen-antibody complexes activate complement, attracting neutrophils that release lysosomal enzymes
Early complement (C1–C4) deficiencies are associated with increased risk of which autoimmune disease?
Systemic lupus erythematosus
A child completes the routine vaccination series for measles, mumps, and rubella (MMR). How long is this protection likely to last?
Throughout his or her life, as vaccines confer active immunity (with long-lasting protection from activation of immune memory)
A patient has a butterfly rash and photosensitivity after initiation of isoniazid therapy. What autoantibodies are specific for this condition?
Anti-histone autoantibodies (this is drug-induced lupus)
How rapidly does hyperacute transplant rejection develop?
Within minutes of transplantation
Which cell surface protein on B cells binds antigen?
Immunoglobulin (Ig)
Goodpasture syndrome, rheumatic fever, and hyperacute transplant rejection exemplify what type II hypersensitivity mechanism?
Inflammation, in which cell opsonization leads to complement system activation and Fc receptor–mediated inflammation
What are the adverse effects of interferon therapy?
Flu-like symptoms, depression, neutropenia, myopathy, interferon-induced autoimmune conditions
Patients with hyper-IgE syndrome (Job syndrome) likely to experience what type of injuries?
Bone fractures, which can result from even minor trauma
List the symptoms of hyper-IgE (Job) syndrome using the mnemonic ABCDEF.
Noninflamed staphylococcal Abscesses, retained Baby teeth, Coarse facies, Dermatologic problems (eczema), high IgE, Fractures from minor trauma (Learn the ABCDEF’s to get a Job!)
Allergic and atopic disorders (eg, rhinitis, hay fever, eczema, hives, asthma) are what type of hypersensitivity reaction?
Type I
Pseudomonas aeruginosa cultures can kill competing bacteria with high levels of reactive oxygen species (ROS). How does this occur?
P aeruginosa produces pyocyanin, which can generate ROS to kill competing microbes
What 2 immunoglobulin (Ig) isotypes are involved in fixation of complement?
IgG and IgM
How can the stimulatory effects of interleukin (IL)-1, IL-2, IL-3, IL-4, IL-5, and IL-6 be summarized?
IL-1 = fever (Hot), IL-2 = T cells, IL-3 = bone marrow, IL-4 = IgE, IL-5 = IgA, IL-6 = aKute-phase proteins (Hot T-bone stEAK)
Which autoantibody is a nonspecific screening marker for several autoimmune disorders, often associated with SLE?
Antinuclear antibody (ANA)
A woman presents with ptosis and muscle weakness that progressively worsens by the end of the day. What antibodies are responsible for this disease?
Autoantibodies against acetylcholine receptors (she has myasthenia gravis)
What gene mutation leads to autosomal dominant hyper-IgE syndrome (Job syndrome)?
STAT3 mutation, which leads to Th17 deficiency, resulting in impaired neutrophil recruitment
Which 2 types of hypersensitivity reactions are implicated in the development of chronic transplant rejection?
Type II and IV hypersensivity (involving both humoral and cellular components)
What are the 3 ways by which antibody-mediated pathogen elimination occurs?
Opsonization, neutralization, and complement activation
Autoimmune hemolytic anemia, ITP, transfusion reaction, and newborn hemolytic disease exemplify which mechanism of type II hypersensitivity?
Cellular destruction in which cells are opsonized and then undergo either NK cell killing or phagocytosis and/or complement system activation
An OR nurse sustains an accidental needlestick injury during a liver transplant procedure on a patient with hepatitis B cirrhosis. What treatment should be given to the nurse?
Combined passive and active immunization (ie, postexposure prophylaxis with preformed anti-HBV antibodies and the recombinant HBV vaccine)
Which 2 cytokines function in the recruitment of immune cells after the initial phase of acute inflammation?
Interleukin-8, interleukin-12; think “acute (IL-1, IL-6, TNF-α), then recruit (IL-8, IL-12)”
Anticardiolipin autoantibodies and the lupus anticoagulant are associated with which disorders?
SLE and antiphospholipid syndrome
A patient develops respiratory distress due to noncardiogenic pulmonary edema within 4 hours of receiving blood products. What is the cause?
Transfusion-related acute lung injury
What lab findings might be seen in patients with C1 esterase inhibitor deficiency?
Decreased C4 level
The phagocyte NADPH oxidase complex utilizes what molecule as a substrate?
Oxygen
A patient is found to be positive for HBsAg and HBeAg and is treated with interferon. What would happen to the number of MHC molecules expressed on his hepatocytes?
Increased concentrations of MHC molecules would be observed (interferons increase MHC expression)
A patient develops worsening edema and necrosis at the site of recent tetanus vaccination. What is the diagnosis?
Arthus reaction: preformed antibodies attack injected antigen leading to formation of immune complexes in the skin and complement activation
A patient with rheumatoid arthritis being treated with a TNF-α inhibitor gradually begins to experience hemoptysis and night sweats. How might this occur?
TNF-α maintains granulomas in TB, so inhibition of this cytokine can lead to reactivation of latent TB
What is the pathogenesis of chronic mucocutaneous candidiasis?
Impaired cell-mediated immunity against Candida classically caused by defects in the AIRE gene; however, various immune system defects may contribute
A patient with poorly controlled eosinophilic asthma is treated with an inhibitor of interleukin-5. How might this drug reduce symptoms of asthma?
Suppression of interleukin-5 will dampen the eosinophilic inflammatory response (as interleukin-5 stimulates eosinophil differentiation)
A 20-year-old man has severe, recurrent pyogenic respiratory tract infections. Which complement disorder should be considered in the differential?
Early complement (C1–C4) deficiencies
What is the main function of interleukin-8?
Promotes neutrophil chemotaxis (“clean up on aisle 8”; neutrophils are recruited by IL-8 to clear infections)
Which vaccine against Salmonella typhi poses a lower risk of causing infection?
The intramuscular Vi polysaccharide typhoid vaccine, which is killed/inactivated
TGF-β has the same attenuating effect on the immune system as which cytokine?
Interleukin-10 (TGF-β and interleukin-10 both attenuate the immune response)
What end product of oxygen-dependent respiratory burst is used to kill bacteria in the phagolysosome?
Bleach (HOCl•), also known as hypochlorite
What is another name for respiratory burst?
Oxidative burst
A patient has a history of several miscarriages and venous thromboses. Labs show prolonged PTT. What autoantibodies are associated with this syndrome?
Anti-β2 glycoprotein I, lupus anticoagulant, and anticardiolipin autoantibodies (she has antiphospholipid syndrome)
A young girl develops hematuria a few weeks after an episode of streptococcal pharyngitis. What type of hypersensitivity reaction is responsible for the disease?
Type III (she has poststreptococcal glomerulonephritis)
