Wk 4: Immunology Flashcards
What are the 2 main types of immunity? Describe them
not important to study, just good to know
1) Adaptive: specific targets (aka acquired)
2) Innate: nonspecific, physical/ physiological barriers (skin, GI lining, gastric acid), phagocytes (neutrophils + macrophages)
What are the 2 types of adaptive immunity? Describe each
not important to study, just good to know
1) Cell mediated: T-lymphocytes
2) Antibody-mediated (humoral): B-lymphocytes (secrete antibodies)
What are immunoglobulins also called? Explain
Used synonymously with antibodies; technically called antibodies when secreted
How are immunoglobulins measured?
In a blood test (mg/dL)
(Reference ranges vary according to age and method)
1) What can immunoglobulins be used for?
2) Is it diagnostic?
1) Can be used to monitor the course of hypersensitivity reactions, immune deficiencies, autoimmune diseases, chronic infections, vaccine responsiveness
2) Serum Ig testing is not diagnostic but can indicate disease
1) What is sometimes required for immunoglobulins?
2) What is this?
1) Follow up electrophoresis
2) Electric current used to separate them according to their mass and charge
What are the 5 immunoglobulin isotypes?
IgG IgA IgM IgE IgD
Differentiate between monoclonal and polyclonal antibodies. What is the difference useful for?
1) Polyclonal: Antibody subtypes that bind to different epitopes of the same antigen
2) Monoclonal: Antibodies of one type that bind to one epitope of the antigen
-Difference is useful in drug development, research, lab evaluation
1) What is the most prevalent Ig?
2) What is noteworthy about it?
1) IgG
2) Crosses placenta
IgG:
1) When may it be increased?
2) When are they present?
3) When may it be deficient?
1) Various disorders including rheumatologic, pulmonary, renal, and immune diseases
2) Immunity via natural or passive
3) Frequent and/or more severe infections
IgA:
1) What % of immunoglobulins does it make up?
2) Where is it present? What is its job?
1) 15% of IG’s in the body
2) Tears, blood, secretions of the respiratory and GI systems
-Protects mucosal tissues from pathogens and maintains homeostasis with microbiota
IgA:
1) When might it be increased?
2) When might it be decreased?
1) Several anti-inflammatory disorders: IgA nephropathy, immunoglobulin A vasculitis (Henoch-Schonlein purpura), acquired immune deficiency syndrome (AIDS), hepatitis, and more
2) Leukemia, macroglobulinemia, IgA deficiency
IgM:
1) What grouping is it responsible for and where is it found?
2) What does it do?
1) ABO blood grouping; in lymph and blood
2) Responds immediately to infection
IgM:
1) What does it form? What does this make it effective at?
2) Does it cross the placenta? Explain
1) “Pentamer” which has 10 antigen-binding sites; effective at forming antigen-antibody complexes and activating complement system
2) Does not cross placenta; elevated IgM in newborn indicates in utero infection
IgE:
1) What does it do?
2) Why is it measured?
3) Where is there overlap in IgE amounts?
4) Is it a good standalone test?
1) Mediates allergic response and parasitic disease
2) Detect allergic disease and hypersensitivity
3) B/t allergic and nonallergic individuals
4) Not useful as a standalone test
IgE:
1) Does it help fight bacterial infections?
2) When is it increased?
1) Not significant in the defense against bacterial infections
Does not activate complement system or participate in opsonization
2) Increased in various diseases: Atopic dermatitis, asthma, immunodeficiency, parasitic infections, viral infections, chronic inflammatory diseases, cancer
Type I hypersensitivity reaction is mediated by what?
IgE mediated
Type I hypersensitivity rxn: what happens during the initial exposure to the antigen (allergen)?
Immune system sensitized:
1) IgE’s with receptors to allergen become linked to mast cells
-Mast cells contain granules rich in histamine (among other things)
Type I hypersensitivity rxn: What 2 things happen during the re-exposure to the antigen (allergen)? What does these cause?
1) Immediate: degranulation of histamine
-Bronchoconstriction, vasodilation
2) Sustained (long-term) response by prostaglandins and leukotrienes
-Chronic inflammation
Give examples of a type 1 hypersensitivity rxn
Bronchial asthma, allergic rhinitis, allergic dermatitis, food allergy, allergic conjunctivitis, drug allergy and anaphylactic shock
Type II hypersensitivity rxn:
1) What mediates it?
2) How many types?
1) IgM IgG mediated
2) 2 types
1) What happens during a type II hypersensitivity rxn? What does this lead to?
2) What else is reacting?
1) Self-cells recognized as foreign; antibodies bind to antigens on person’s own cells
-Leads to autoimmune cellular destruction
2) Reactions to non-self cells too
Give 4 examples of type II hypersensitivity rxns
1) Transfusion reaction after receiving incompatible blood
2) Graves’s disease: antibodies target TSH receptors
3) Immune thrombocytopenia: antibodies target platelets
4) Many other autoimmune examples
Type III hypersensitivity rxn:
1) What mediates it?
2) What happens?
1) IgG mediated
2) Antibodies bind to circulating antigens but are not effectively cleared
-Antigen-antibody complexes deposit in vessels and joints
-Leads to localized inflammatory reactions
Type III hypersensitivity rxn: give examples
1) Rheumatoid arthritis
2) Post streptococcal glomerulonephritis
3) Systemic lupus erythematosus
Immune complex reaction is also called what?
Type III hypersensitivity rxn
Type IV hypersensitivity rxn:
1) What mediates it?
2) What happens?
3) What is it also called?
1) T-cell mediated (not antibody mediated)
2) T-cells overreact to antigens which leads to exaggerated immune response, inflammation, tissue damage
3) Delayed rxn (takes days to develop)
Give 3 examples of a type IV hypersensitivity rxn
1) Allergic contact dermatitis
2) Type 1 DM: pancreatic beta cell destruction
3) Inflammatory bowel disease
What is the way to remember the 4 types of hypersensitivity rxns?
I) Allergic, anaphylaxis, and atopy
II) antiBody
III) immune Complex
IV) Delayed
1) What does autoimmune mean? What causes it?
2) What 3 things are elevated in general with an autoimmune condition?
1) Overreactive immune system; T-cell and B-cell activity leading to harmful processes against own tissues
3) Elevated inflammatory markers (ESR/CRP)
-Elevated WBCs
-Elevated antibodies sometimes
1) What does immunodeficiency mean?
2) What are some generalizations you can make abt patients with this?
1) Inadequate immune system
2) Frequent, opportunistic, or exaggerated infections
-Decreased WBCs, decreased antibodies
Describe immunodeficiency conditions
Many disorders:
-Clinical experience uncommon (disease is rare or patient dies from the disease)
-Grouping and memorization is difficult
-Pathology and testing varies widely
Human Immunodeficiency Virus:
1) What is it?
2) What does it affect?
1) Virus that leads to progressive immune system failure, increasing risk of infections and cancers
2) CD4 (“cluster of differentiation 4”)
Human Immunodeficiency Virus:
1) What is protein on surface of immune cells, especially helper T cells, important in?
2) What does HIV lead to?
1) Important in signaling CD8 which aids cytotoxic T cells
2) Progressive reduction in CD4+ T cells
1) Is CD4 a direct test of HIV?
2) What does lower CD4 mean? What abt higher CD4?
3) Does it vary?
4) What makes AIDS AIDS?
1) Not a direct test of HIV but used to measure progress
2) Lower CD4 counts mean increased risk of opportunistic infections
-Increase in CD4 counts indicate successful treatment
3) Relatively significant variation in normal values even in a single person
4) CD4 count below 200 = AIDS
How can a pt with HIV be diagnosed?
1) HIV differentiation immunoassay (HIV serology): -Confirms HIV and distinguishes type; many types of tests
2) ELISA: Enzyme-Linked ImmunoSorbent Assay
-Detect antibody to HIV and others
3) CBC: Leukopenia, lymphopenia
-Thrombocytopenia: infections can suppress bone marrow
What is needed next once HIV is diagnosed?
HIV RNA quantification (HIV viral load): Quantifies HIV RNA in patients after diagnosis is confirmed
-Used with CD4 count to direct treatment approach
1) Blood types depend on what?
2) Explain ABO blood typing
1) Surface antigens on erythrocytes
2) Human erythrocytes have inherited antigens of A, B, or both A and B
-Or lack of AB surface antigens (O)
1) Type A blood contains _________________________
2) Type B blood contains ________________________
3) Type AB blood contains ________________________
4) Type O blood contains _______________________
1) Anti-B antibodies
2) Anti-A antibodies
3) No antibodies
4) Anti-A and anti-B antibodies
Rh factor:
1) An erythrocyte antigen first discovered in _______________
2) Do the antibodies to this antigen occur naturally?
1) Rhesus monkeys
2) Antibodies to the antigen do not occur naturally, developed after first exposure in Rh- individuals to Rh+ blood
Transfusion rxn:
1) When does it occur?
2) How many rxns is it?
1) Exposure to incompatible blood
2) Two antigen-antibody reactions
Transfusion rxn: List and explain the 2 reactions going on
1) Recipient’s plasma antibodies vs donor’s erythrocyte antigens
-Agglutination reaction (clumping) and hemolysis of RBCs
-Can be fatal
-Blocks vessels, released Hgb can block kidneys causing acute kidney failure
2) Donor’s plasma antibodies vs recipient’s erythrocyte antigens
-Less important because donor’s antibodies are diluted by recipient’s plasma, causing little RBC damage
Coombs Tests: What are they? Explain
1) Checks your blood for antibodies against RBCs (jaundice, anemia)
2) Aka antiglobulin tests (AGT); animal (rabbit) injected with human plasma. Develops anti-human antibodies.
-Antibodies against human antibodies = “Coombs reagent”
3) RBCs and plasma separated
What are the 2 types of Coombs tests? Explain
1) Direct: Tests the RBCs to detect antibodies
-“Are there antibodies against RBCs in this patient?”
2) Indirect: Tests the serum to detect antibodies
-“What are those antibodies attacking?”
-Only used in gravid women and testing prior to blood transfusion “Type & Screen”
Direct Coombs test (DAT)
1) What does it do?
2) Give examples of when it’s useful
1) Confirms immune-mediate hemolytic anemia
2) Autoimmune hemolytic anemia, transfusion reaction, HDN, etc
Direct Coombs test (DAT):
1) How is it done?
2) What is a positive result?
3) What is a negative?
1) Coombs reagent added to patient’s RBCs
“Are there antibodies attacking this patient’s RBCs?”
2) Yes: Coombs reagent will bind to the antibodies attacking RBCs = clumping =+DAT
3) No: no clumping = -DAT
Indirect Coombs test (IAT)
1) What is it?
2) Give an example
1) Patient’s serum is systematically exposed to RBCs with predetermined antigens
2) Ex: Serum with RBCs of types A B AB X Y Z etc
-If AB and A antigen tests result in clumping but not B or O then we know there are anti-A antibodies in patient’s plasma
Indirect Coombs test (IAT):
1) What does clumping mean?
2) If AB and A antigen tests result in clumping but not B or O then we know what?
1) Tests that result in clumping confirm presence of antibodies against those antigens
2) There are anti-A antibodies in patient’s plasma
What is a type and screen?
1) Determines ABO grouping and Rh typing
2) Also, other more common antibodies
Type and cross:
1) What does it include?
2) When is it ordered?
3) How long does it take? Explain
1) Includes type and screen + adding recipient plasma to donor blood to see if there is a reaction (indirect Coombs test)
2) If there is high likelihood of transfusion
3) Takes about 1 hour. May be skipped in emergencies.
-Risk of emergency condition outweighs risk of transfusion reaction
-O- blood may be used. Depends on institution’s policies.
Blood product indications: who needs whole blood?
1) Not clinically efficient. Most patients require a specific element.
2) Components can be separated and stored under separate ideal conditions.
Blood product indications: who needs packed RBCs?
Very low Hgb, decreased O2 sat, need for additional O2 capacity (chronic anemia, cardiopulmonary disease, acute blood loss)
Blood product indications: who needs platelet rich plasma (PRP)?
1) Low platelets at risk of spontaneous bleeding.
2) May be given before high-risk procedures, thresholds for risk and platelet count vary.
-try to minimize the number of donors
Blood product indications: who needs fresh frozen plasma and what does it contain?
1) Used for patients with bleeding and clotting factor deficiencies. Typically, INR at least 1.6.
2) Contains clotting factors.
Blood product indications: what is cryoprecipitate and who needs it?
1) FFP is thawed and centrifuged, precipitate is re-frozen.
-Fewer total clotting factors but more concentrated with select factors
-Factors 8 and 13, fibrinogen, von Willebrand factor
2) More useful than FFP if patient is deficient in those specific factors
