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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 is chronic mucocutaneous candidiasis d/t?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
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
type four
T cell dysfunction

2. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Histamine; post capillary venules - vasodilation
Axillary
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
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

3. What is epo used for?
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
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Anemias (esp due to renal failure)

4. What is oprelevkin? and What is it used for?
Previous transfusion; pregnant woman whose fetus had paternal antigens
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Recom IL 11; thrombocytopenia

5. what cell surface proteins are on all APCs?
Interferon gamma and IL 2
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Cyclosporine - OKT3
MHC II - B7

6. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Hemochromatosis
Remove encapsulated bacateria
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Active; passive - fast but short half life (3 weeks!)

7. which cells have more complete tolerance - B or T cells?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
T
A chemotactic factor for neutrophils
Th2; Th1

8. What are the autoantibodies for Celiac disease?
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
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Negative!

9. other than C3a - what other complement acts as an anaphyloxin?
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
C5a
DM type I
Activates cytotoxic CD 8 T cells as second signal

10. The ______ in the BM are DN - the DP are in the cortex of thymus
IgG
T cell precursor
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
It is a localized type III hypersensitivity reaction to an external antigen; localized instead of systemic; ?; intradermal injection of the antigen results in antibody production and antigen antibody complexes deposit in the skin

11. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
IgA
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Axillary
Increases expression of MHC I and MHC II and also activates NK cells

12. What are the three types of APCs?
IgA
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Macrophages - Dendritic cells - B cells
IgM and IgD

13. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Recom IL 11; thrombocytopenia
TGF beta and IL 10
Secretory component
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

14. The pathogenesis of contact dermatitis is ________ hypersensitivity
No! That is why they are different from T cells - they can recognize antigens in free solution; if a bug has a peptide fragment that a mature naive B cell recognizes it will bind to it and cause activation - it then gets activated into a plasma cell!
MS
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
type four

15. Type Iv hypersensitivity is...
A j chain
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
delayed!
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

16. Complements are...
acute phase reactants
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
Antibody mediated cytotoxicity; either complement dependent or complement independent
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

17. What are C1 - C2 - C3 - C4 important for?
Chronic granulomatous disease
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
IL 3; supports growth and differentiation of bone marrow stem cells
Viral neutralization of igM and IgG!

18. What type of fenestrations are found in the red pulp of the spleen?
Interferon gamma; Th1
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Barrel hoop basement membrane fenestrations
Type III hypersensitivity where an exogenous antigen results in a systemic antigen antibody complex disease (takes around 5 days after exposure for the Abs to develop); immune complexes then fix in tissue and activate complement resulting in tissue d

19. Which antibody mediates immunity to worms? how?
IgE; by activating eosinophils
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Popliteal
Anti TSh receptor

20. What are the T cell functions?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
CD21 on B cells (although there is T cell lymphocytosis in EBV)
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

21. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Its main effect is a defect in Ab opsonization for killing
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
Into cortex and medulla; cortex is where immature T lymphocytes enter - at the corticomedullar junction is where positive and negative selection occur; and at the medulla is where the mature T lymphs - reticulin cells and hassalls corpuscles are (dea
Paracortex; viral infection

22. What is the receptor for EBV? On what cells is that located?
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
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
The patient could become cyanotic in the OR!
CD21 on B cells (although there is T cell lymphocytosis in EBV)

23. What is the most common selective Ig deficiency? What is the presentation?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
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
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
...

24. What is the main function of interferons?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Acts as second signal on B cells to induce class switching to IgE and IgG
acute phase reactants
Anti U1 RNP (ribonucleoprotein)

25. where do somatic hypermutation and class switching occur?
In the germinal center of secondary follicles (In the paler center)
Interferon gamma and IL 2
secondary
Remove encapsulated bacateria

26. Describe complement dependent Type II hypersensitivity. Give an example.
Anti IF
T cell dysfunction
IgM or IgG antibodies coat the antigen and result in activation of MAC complex via the classical pathway OR fixed macrophages in the spleen phagoctyose the opsonized (C3b or igG) antigens - ex penicillin reaction; IgM AIHA - anti B IgMs in a group A
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

27. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
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
False! B cell class switching requires a second signal
except hyperacute

28. when can graft versus host disease? What is the result?
In any situation where immunologically competent cells are transplanted into immunologically crippled recipient; graft rejects all the cells due to foreign proteins resulting in severe organ dysfunction
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Antidesmoglein
IgAs in mothers breast milk!

29. Give three examples of bacteria that use antigenic variation and how.
IgG
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Celiac
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

30. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Edema and necrosis in that region
Sinusitis - otitis media - pneumonia
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

31. Which type of selection of thymic development provides central tolerance?
Anti alpha subunit 3 of collagen on type IV bm
IL 1 and IL 6
Negative selection
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

32. What lymph node drains the duodenum - jejunum?
Superior mesenteric
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
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
2 heavy chains and two light chains

33. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
Barrel hoop basement membrane fenestrations
...
Its a serine protease that activates apoptosis; NK and CD8
IgG

34. can igG cross the placenta?
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Yes

35. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
Sinusitis - otitis media - pneumonia
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
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
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

36. which antibodies prevent antigens from binding mucosal surfaces?
IgA
Anti topoisomerase
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
MHC class molecules bind to KIRS or CD94 to prevent killing

37. What cytokines are released by Th1 cells?
S. aureus - E. Coli - aspergillus
MHC class molecules bind to KIRS or CD94 to prevent killing
High endothelial venules are post capillary cuboidal endothelial cells that contain specific adhesion molecules for lymphocytes with specific binders that allows for lymphocytes to drain out of the vasculature into the lymph node structure (this is h
Interferon gamma and IL 2

38. Describe the complement independent Type II hypersenstivity reaction. Give an example.
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
IgM or IgG antibodies coat the antigen and result in activation of MAC complex via the classical pathway OR fixed macrophages in the spleen phagoctyose the opsonized (C3b or igG) antigens - ex penicillin reaction; IgM AIHA - anti B IgMs in a group A
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

39. Name the three opsonins
Lymphocytes
Its a serine protease that activates apoptosis; NK and CD8
CRP - C3b - IgM
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

40. What is the most common example of passive immunity?
IgAs in mothers breast milk!
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
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
Active; passive - fast but short half life (3 weeks!)

41. in which immunodef order do you see a lot of pus? no pus?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
False! B cell class switching requires a second signal
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
When you select for which MHC it will have; take out the lymphs that self react

42. How fast does it occur?
The patient could become cyanotic in the OR!
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Superior mesenteric
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

43. What is the pathology seen in chronic transplant rejection?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

44. Which disease is associated with B8?
Graves
Anti topoisomerase
The patient could become cyanotic in the OR!
MHC class molecules bind to KIRS or CD94 to prevent killing

45. How does igA cross the epithelium?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
active complement pathway
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
By transcytosis

46. What does it mean if there are igM in the serum at birth?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
IgM and IgG
Graves
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

47. What is thrombopoietin used for?
Thrombocytopenia
Inferior mesenteric
Popliteal
IgAs in mothers breast milk!

48. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IgG
Barrel hoop basement membrane fenestrations
Superficial inguinal

49. what bacteria are a splenectomy patient most susceptible to? why?
Interferon gamma and IL 2
isotype
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
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

50. Monomer in circulation - ___ when secreted
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
dimer
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear