Immuno FA part II p109 - 122 Flashcards
What makes sputum a green color?
Myeloperoxidase contains a blue-green, heme-containing pigment that gives sputum its color.
Patients with CGD are at risk for infection of what organisms?
Catalase + organisms -
Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E coli, Staphylococci, Serratia, B cepacia, H pylori.
Cats Need PLACESS to Belch their Hairballs.
Enzyme def in Chronic granulomatous disease? Inheritance pattern?
Defect of NADPH oxidase –> dec reactive oxygen species (eg, superoxide) and –> dec respiratory burst in neutrophils; X-linked form most common.
_____ plays a role in both the creation and neutralization of ROS.
NADPH
How do catalase + organisms prevent respiratory burst in pts with CGD?
catalase ⊕ species (eg, S aureus, Aspergillus) capable of neutralizing their own H2O2, leaving phagocytes without ROS.
_____ of _____ generates ROS to kill competing pathogens
Pyocyanin of P aeruginosa generates ROS to kill competing pathogens
Oxidative burst also leads to ____ influx, which releases __________.
Oxidative burst also leads to K+ influx, which releases lysosomal enzymes.
_______ is a protein found in secretory fluids and neutrophils that inhibits microbial growth via ____ _________
Lactoferrin is a protein found in secretory fluids and neutrophils that inhibits microbial growth via iron chelation
How to interferons fight virus infections?
by downregulating protein synthesis to resist potential viral replication and by upregulating MHC expression to facilitate recognition of infected cells.
Clinical use of Interferons
Chronic HBV and HCV, Kaposi sarcoma, hairy cell leukemia, condyloma acuminatum, renal cell carcinoma, malignant melanoma, multiple sclerosis, chronic granulomatous disease.
Cell surface proteins on T cells
TCR (binds antigen-MHC complex)
CD3 (associated with TCR for signal transduction) CD28 (binds B7 on APC)
Cell surface proteins of Th cells?
CD4, CD40L, CXCR4/CCR5 (co-receptors for HIV)
Tc cell surface proteins?
CD8
Treg cell surface proteins?
CD4, CD25
B cell - cell surface proteins?
Ig (binds antigen)
CD19, CD20, CD21 (receptor for Epstein-Barr virus), CD40
MHC II, B7
Macrophages - cell surface proteins?
CD14 (receptor for PAMPs, eg, LPS), CD40
CCR5
MHC II, B7 (CD80/86)
Fc and C3b receptors (enhanced phagocytosis)
NK cells - cell surface proteins and fxn?
CD16 (binds Fc of IgG),
CD56 (suggestive marker for NK)
Hematopoietic stem cells - cell surface proteins?
CD34
What is anergy?
State during which a cell cannot become activated by exposure to its antigen. T and B cells become anergic when exposed to their antigen without costimulatory signal (signal 2). Another mechanism of self-tolerance.
Passive vs Active immunity - means of acquisition
passive - receiving preformed antibodies
active - exposure to foreign antigens
Onset of action and duration of Passive vs Active immunity?
Examples of Passive vs Active immunity
Passive - IgA in breast milk, maternal IgG crossing placenta, antitoxin, humanized monoclonal antibody
Active - natural infection, vaccines, toxoid
Combined passive and active immunizations can be given for exposure to what?
hepatitis B or rabies
Live attenuated vaccines - (+) what immune response? Pros? and Cons?
Induces cellular and humoral responses.
Pros: induces strong, often lifelong immunity.
Cons: may revert to virulent form. Often contraindicated in pregnancy and immunodeficiency.
If HIV patients CD4 cell count >= 200cells/mm^3, what vaccines are given? what type?
MMR and varicella vaccines can be given to HIV ⊕ patients without evidence of immunity if CD4 cell count ≥ 200 cells/ mm3.
- live attenuated vaccine
Ex of live attenuated vaccines?
Adenovirus (nonattenuated, given to military recruits), Typhoid (Ty21a, oral), Polio (Sabin), Varicella (chickenpox), Smallpox, BCG, Yellow fever, Influenza (intranasal), MMR, Rotavirus
“Attention Teachers! Please Vaccinate Small, Beautiful Young Infants with MMR Regularly!”
Killed or inactivated vaccine - induces what kind of immune response? Pros/Cons?
Pathogen is inactivated by heat or chemicals. Maintaining epitope structure on surface antigens is important for immune response. Mainly induces a humoral response.
Pros: safer than live vaccines.
Cons: weaker immune response; booster shots usually required.
Examples of killed vaccines?
Rabies, Influenza (injection), Polio (Salk), hepatitis A, typhoid (Vi polysaccharide, intramuscular)
SalK = Killed
RIP Always
What is a subunit vaccine?
Includes only the antigens that best stimulate the immune system.
Ex of subunit vaccine?
HBV (antigen = HBsAg),
HPV (types 6, 11, 16, and 18),
acellular pertussis (aP),
Neisseria meningitidis (various strains), Streptococcus pneumoniae,
Haemophilus influenzae type b.
What is a toxoid vaccine? Pros/Cons?
Denatured bacterial toxin with an intact receptor binding site. Stimulates the immune system to make antibodies without potential for causing disease.
Pros: protects against the bacterial toxins. Cons: antitoxin levels decrease with time, may require a booster.
Ex of toxoid vaccine
Clostridium tetani,
Corynebacterium diphtheriae
List types of hypersensitivity reactions - which are are antibody mediated?
Four types (ABCD): Anaphylactic and Atopic (type I), AntiBody-mediated (type II), Immune Complex (type III), Delayed (cell-mediated, type IV). Types I, II, and III are all antibody-mediated.
Two phases of HS-I?
Anaphylactic and atopic—two phases:
Immediate (minutes): antigen crosslinks preformed IgE on presensitized mast cells –> immediate degranulation –> release of histamine (a vasoactive amine) and tryptase (a marker of mast cell activation).
Late (hours): chemokines (attract inflammatory cells, eg, eosinophils) and other mediators (eg, leukotrienes) from mast cells –> inflammation and tissue damage.
How to test for HS-I?
Test: skin test or blood test (ELISA) for allergenspecific IgE
What happens in type II HS?
Antibodies bind to cell-surface antigens –> cellular destruction, inflammation, and cellular dysfunction.
HS-II - cellular destruction happens how? Diseases where this happens?
Cellular destruction—cell is opsonized (coated) by antibodies, leading to either:
Phagocytosis and/or activation of complement system.
NK cell killing (antibody-dependent cellular cytotoxicity).
Ex/ Autoimmune-hemolytic anemia Immune thrombocytopenia Transfusion reactions Hemolytic disease of the newborn
HS-II - how inflammation occurs? Diseases where this happens?
Inflammation—binding of antibodies to cell surfaces –> activation of complement system and Fc receptor-mediated inflammation.
Ex/ Goodpasture syndrome Rheumatic fever Hyperacute transplant rejection
HS-II - how does cellular dysfunction happen? Diseases where this process happens?
Cellular dysfunction—antibodies bind to cell surface receptors –> abnormal blockade or activation of downstream process.
ex/ Myasthenia gravis Graves disease Pemphigus vulgaris
HS-III - what happens?
Immune complex—antigen-antibody (mostly IgG) complexes activate complement, which attracts neutrophils; neutrophils release lysosomal enzymes.
In type III reaction, imagine an immune complex as 3 things stuck together: antigenantibody-complement.
Ex of diseases with HS-III?
SLE Polyarteritis nodosa Poststreptococcal glomerulonephritis
What happens in serum sickness? sx?
Serum sickness—the prototypic immune complex disease. Antibodies to foreign proteins are produced and 1–2 weeks later, antibodyantigen complexes form and deposit in tissues –> complement activation –> inflammation and tissue damage.
Fever, urticaria, arthralgia, proteinuria, lymphadenopathy occur 1–2 weeks after antigen exposure.
Serum sickness- like reactions are associated with which drugs/infections?
penicillin, hep B
What’s an arthus reaction?
Arthus reaction—a local subacute immune complex-mediated hypersensitivity reaction. Intradermal injection of antigen into a presensitized (has circulating IgG) individual leads to immune complex formation in the skin. Characterized by edema, necrosis, and activation of complement.
Two mech of HS-IV?
- Direct cell cytotoxicity: CD8+ cytotoxic T cells kill targeted cells.
- Inflammatory reaction: effector CD4+ T cells recognize antigen and release inflammation-inducing cytokines (shown in illustration).
T or F HS-IV response does not involve antibodies
True! (Type 1, 2,3 do)
Ex of HS-IV?
contact dermatitis (eg, poison ivy, nickel allergy) and graft-versus-host disease.
[MS, T1DB, Hashimoto]
Tests: PPD for TB infection; patch test for contact dermatitis; Candida skin test for T cell immune function.
4T’s: T cells, Transplant rejections, TB skin tests, Touching (contact dermatitis)
Explain the allergic/anaphylactic reaction to blood transfusion? sx? timing?
Type I hypersensitivity reaction against plasma proteins in transfused blood. IgA deficient individuals must receive blood products without IgA.
Sx/ Urticaria, pruritus, fever, wheezing, hypotension, respiratory arrest, shock.
Within minutes to 2-3 hours
Explain acute hemolytic transfusion reaction? What type of HS? Sx? timeline?
- *Type II hypersensitivity reaction.**
- *Intravascular hemolysis** (ABO blood group incompatibility) or extravascular hemolysis (host antibody reaction against foreign antigen on donor RBCs).
Sx/Fever, hypotension, tachypnea, tachycardia, flank pain, hemoglobinuria (intravascular hemolysis), jaundice (extravascular).
Within 1 hr
Explain mech of febrile non hemolytic transfusion reaction?
febrile non hemolytic transfusion reaction:
Two known mechanisms: most likely induced by cytokines that are created and accumulate during the storage of blood products; or associated with type II hypersensitivity reaction with host antibodies directed against donor HLA and WBCs.
Sx and timeline of febrile nonhemolytic transfusion rxn?
sx/ Fever, headaches, chills, flushing. Reaction prevented by leukoreduction of blood products.
Within 1-6 hrs
Transfusion related acute lung injury - mech and sx? timeline?
Transfusion related acute lung injury :
Donor anti-leukocyte antibodies against recipient neutrophils and pulmonary endothelial cells.
sx/ respiratory distress and noncardiogenic pulmonary edema
within 6 hours
X-linked (Bruton) agammaglobulinemia
Defect in BTK, a tyrosine kinase gene no B-cell maturation. X-linked recessive (Inc in Boys).
What disease leads to inc susceptibility to giardiasis?
Selective IgA def
Presents after age 2, with risk of autoimmune disease, bronchiectasis, lymphoma and sinopulm infections
CVID
Dec immunoglobulins on blood work - of any type
X linked agammaglobulinemia - no B cell maturation
CVID - no B cell differ’n
Pt has no lymph nodes or tonsils - primary follicles and germinal centers absent
X linked agammaglobulinemia
Which immunodef can present with hypocalcemia? why? whats the sx?
Thymic aplasia - ex/DiGeorge syndrome bc of No PTH hormone –> leads to tetany