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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Cross link
pentamer
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
delayed!

2. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
type four
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
In IgE AIHA- it results in MAC attack (remember IgE is not an opsonin!) - in IgG AIHA C3b (and IgG) opsonization results in phagocytosis by fixed macrophages in the spleen

3. What is the presentation of common variable immunodef? and What are the labs?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Daclizumab; prevent ACUTE rejection of renal transplant
Antidote for digoxin intoxication
Can be acquired in 20s -30s; increased risk of autoimmune disease - lymphoma - Sp infections; normal number of B cells and no plasma cells and immunoglobulin

4. What is oprelevkin? and What is it used for?
Pernicious Anemia and Hashimotos
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs
Immunosuppression after kidney transplantation
Recom IL 11; thrombocytopenia

5. Type Iv hypersensitivity is...
delayed!
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
pale central germinal centers
An acidified endosome with the antigen fuses with the MHC which causes the release of the invariant chain Which is sitting in spot of antigen and stabilizing the MHC II

6. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
TNF alpha and IL1
Anti TSh receptor
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

7. How does complement link innate and adaptive?
Previous transfusion; pregnant woman whose fetus had paternal antigens
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

8. What lymph node drains the testes?
A chemotactic factor for neutrophils
Para aortic
Hours later (instead of minutes); instead of release of preformed mediators - mast cells synthesize PGs and LTs that mediate the late phase reaction (edema - inflammation - decreased airflow)
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

9. What are the autoantibodies for graves?
Anti TSh receptor
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
...
CRP - C3b - IgM

10. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
MAC (membrane attack complex) Which is activated by C5b - C9 and results in lysis and cytoxicity by creating pores in the target membrane; encapsulated organisms (S. pnuemonia - H.influenzae - B perfussis for example) and other organisms with non pep
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
...
Antimicrosomal and antithyroglobulin

11. What are the autoantibodies for Celiac disease?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
A chemotactic factor for neutrophils
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

12. which immunodeficiency presents with delayed separation of the umbilicus? ataxia? telangiectasia?albinism? anaphylaxis on exposure to blood products with IgA? tetany?retained primary teeth? peripheral neuropathy?
Defect in LFA 1 integrin (CD 18) protein on phagocytes (neutrophils!); recurrent bacterial infections - severe gingivitis - poor wound healing - absent pus formation - and delayed separation of the umbilicus; neutrophilia
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Fab portion
Viral neutralization of igM and IgG!

13. What are four results of a splenectomy?
Para aortic
Macrophages - Dendritic cells - B cells
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

14. What are superantigens? give two examples.
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
The interstitial tissue of a lymph node is structured into the cortex on the outside Which is densely cellular which transitions into the paracortex Which is less dense and then the medulla Which is least dense. The cells that inhabit these tissues a
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
CROSS LINK Beta region on TCR of CD4 cells to the MHC class II on APCs this results in uncoordinated release of Interferon gamma from CD4 Th1 cells and subsequent release of IL1 - IL6 and TNF alpha from Macrophages --> toxic shock syndrome; s. pyogen

15. IgG...
opsonizes
Digeorge syndrome - 22q11 deletion resulting in failure to develop 3rd and 4th pharyngeal pouches; cardiac and great vessel congenital defects - tetany from hypocalcemia - recurrent viral/fungal infections from T cell deficiency; hypoPTH - hypoCa - a
B - T - and NK cells
Graves

16. in which immunodef order do you see a lot of pus? no pus?
They directly stimulate Macrophages by binding CD14; also the alternative complement pathway binds to these host surfaces and induces MAC complex; also TLRs exist for endotoxins; also IgM though not an opsonin can act as a pentamer and trap the antig
Receiving preformed Antibodies
The igA found in breast milk
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

17. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
heavy chains
opsonizes

18. What does IL 2 do?
Activates cytotoxic CD 8 T cells as second signal
MHC I; from RER with help of the B2 microglobulin
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Chronic granulomatous disease

19. which antibody activate mast cells - basophils - and eosinophils?
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
IgE
Found in the red pulp; contains the cords of billroth or the splenic parenchyma that have APCs/Macrophages that closely interact with the basement membrane of the vasculature and where RBCs squeeze through into the parenchyma and interact with Macrop
The igA found in breast milk

20. What does IgA pick up from epithelial cells before being secreted?
Binds to Mtor which (like tacrolimus and cyclosporine just in a different pathway) inhibits IL 2 production and thus t cell proliferation in response to IL 2 producton
CD56
Secretory component
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

21. What is the pathology seen in chronic transplant rejection?
If there is class switching and plasma cell production (that is when memory cells are produced)
Anti alpha subunit 3 of collagen on type IV bm
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Recom IL 11; thrombocytopenia

22. which antibodies can bind complement?
Binds to Mtor which (like tacrolimus and cyclosporine just in a different pathway) inhibits IL 2 production and thus t cell proliferation in response to IL 2 producton
DM type I
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
IgM and IgG

23. which of the transplant rejections is antibody mediated? why does it occur?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Anti topoisomerase
Anti IF
2 heavy chains and two light chains

24. What does granzyme do? who secretes it?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Its a serine protease that activates apoptosis; NK and CD8
IL 4

25. What are the cell surface proteins on NK cells?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
MHC I - CD16 - CD56
Yes
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

26. What is epo used for?
All MHC 1/CD8
Anti mitochondrial
Anemias (esp due to renal failure)
Th cells fail to produce interferon gamma; a lot of IgE

27. What lymph node drains the thigh?
Superficial inguinal
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Antibody mediated cytotoxicity; either complement dependent or complement independent
Cytokine IL 10 secreted by Th2

28. give an example of how influenza does a major antigenic shift.
...
Steroid responsive nephrotic syndrome
Anti viral and anti tumor
RNA segment reassortment

29. The lymphocytes are ________ origin
Capsule of lymph node is made up of type III collagen (made by reticulin fibers!) - extension of this collagen extends into the splenic tissue as trabeculae; nonspecific filtration of lymph by Macrophages - Antibody production (via activation) - stor
mesenchymal
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Anti TSh receptor

30. What is the main function of TNF alpha? How does it do this?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Complement activation (active in both)
Not thymus - BM
Activate macrophages

31. Which cytokines do Th2 release and For what?
heavy chains
encapsulated
Binds to Mtor which (like tacrolimus and cyclosporine just in a different pathway) inhibits IL 2 production and thus t cell proliferation in response to IL 2 producton
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

32. So antibodies are the effectors for the humoral response. List some of their functions.
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Secretory component
dimer

33. What is a factor that is a predictor for a bad transplantation?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
1) VJ light chain random creation 2) VDJ (heavy chain) random creation 3) random combination of light with heavy 4) somatic hypermutation (high frequency mutating that occurs on activation) 5) terminal deoxynucleotidyl transferase (TDT) random additi
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
An antigen encounter (presented by APC for Th2) with Th2 will result in it to go to the cortical section and help with B cell activation; Cytotoxic T cell will enter vasculature/efferent lymph to go kill; B cell will wait for Th2 for activation and t

34. What is a type I hypersensitivity reaction? What is atopic?
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Antidesmoglein

35. Type IV hypersensitivity is i...
Maculopapular rash (palm - soles - back - neck) - jaundice with bile duct necrosis - hepatosplenomegaly - diarrhea; bone marrow and liver transplants (rich with lymphocytes); SCID patient receiving whole blood transfusion
Stimulate the liver to release acute phase reactants
not Ab mediated
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

36. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
A - B - C; all the D's
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
If there is class switching and plasma cell production (that is when memory cells are produced)
IgM and IgA

37. what mediates the type II hypersensitivity? What are the two different methods?
Antibody mediated cytotoxicity; either complement dependent or complement independent
Rheumatic arthritis
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs
Secretory component

38. What lymph node drains the stomach?
Celiac
2 heavy chains and two light chains
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
IgM

39. what happens in a deficiency of C1 esterase inhibitor? DAF?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Hereditary angioedema; PNH
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Capsule of lymph node is made up of type III collagen (made by reticulin fibers!) - extension of this collagen extends into the splenic tissue as trabeculae; nonspecific filtration of lymph by Macrophages - Antibody production (via activation) - stor

40. Describe the Mannose Lectin pathway
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Type IV
T cell precursor
Some microbial surfaces (only) have mannan binding lectin which activates a protease that cleaves C2 and C4 which combine to make C3. the rest follows the alternative pathway

41. What are the autoantibodies for primary biliary cirrhosis?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Anti mitochondrial
Fab portion
Tetanus - Botulinum - HBV - Rabies

42. What do multimeric antibodies require for assembly?
MS
A j chain
...
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

43. What are the autoantibodies for pernicious anemia?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Anti IF
Anti Ach receptor
N. meningitidis - H. influenzae - S. pneumonia - Salmonella d/t lack of C3b opsonization for MAC d/t lack of complement activation d/t lack of IgM; MAC is needed by encapsulated avoid by humoral and cell mediated through their capsule

44. Which MHC presents intracellular peptides? how so?
mesenchymal
Digeorge syndrome - 22q11 deletion resulting in failure to develop 3rd and 4th pharyngeal pouches; cardiac and great vessel congenital defects - tetany from hypocalcemia - recurrent viral/fungal infections from T cell deficiency; hypoPTH - hypoCa - a
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
MHC I; from RER with help of the B2 microglobulin

45. What is the common variable immunodeficiency ? How is it different from Brutons?
Anti Ach receptor
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs
MHC I; from RER with help of the B2 microglobulin
Cytokine IL 10 secreted by Th2

46. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Complement activation (active in both)
Th cells fail to produce interferon gamma; a lot of IgE
Acts as second signal on B cells to induce class switching to IgE and IgG
Activate macrophages

47. What is wiskott aldrich syndrome? What is its mode of inheritance? What is the pathogenesis of disease? What is its triad of presentation? what labs does it present with?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Anti topoisomerase
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
A B and T cell disorder; X linked recessive; progressive deletion of B and T cells; thrombocytopenic purpura - infections - eczema; high IgE and IgA but low IgM

48. What does interferon gamma do? What two type of cells does it attack mostly?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Can be acquired in 20s -30s; increased risk of autoimmune disease - lymphoma - Sp infections; normal number of B cells and no plasma cells and immunoglobulin
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

49. What is the late phase reaction of anaphylaxis allergy? what mediates it?
T cell dysfunction
Negative!
Superficial inguinal
Hours later (instead of minutes); instead of release of preformed mediators - mast cells synthesize PGs and LTs that mediate the late phase reaction (edema - inflammation - decreased airflow)

50. What are the three types of APCs?
Previous transfusion; pregnant woman whose fetus had paternal antigens
Macrophages - Dendritic cells - B cells
Negative nitroblue tetrazolium reduction test
Anti IF