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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.
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. ________ regulate the cell mediated response.
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Humoral
Celiac

2. What are target cells?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Cells that stil have weird parts of their membrane that macrophages usually bite off
Active; passive - fast but short half life (3 weeks!)
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

3. what will NK cells do to cells covered in IgG Ab? why?
...
Kill them because they have CD16 on them that recognize the FcG portion
encapsulated
Steroid responsive nephrotic syndrome

4. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
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
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
IgA
secondary

5. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
IL 4
...
TNF alpha and IL1
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

6. IgM can fix complement but...
cannot cross placenta
Celiac
Cross link
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

7. What are the autoantibodies for hashimotos?
Cross link
Wiskott Aldrich syndrome
Antimicrosomal and antithyroglobulin
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

8. 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
Antidote for digoxin intoxication
Type IV
carboxy terminal

9. What is the main function of IL 8?
A chemotactic factor for neutrophils
Interferon gamma and IL 2
IgG
Popliteal

10. What is passive immunity?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Receiving preformed Antibodies
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
isotype

11. How is i Th1 helper cell inhibited?
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Cytokine IL 10 secreted by Th2
heavy chains

12. The ______ in the BM are DN - the DP are in the cortex of thymus
Superficial inguinal
T cell precursor
Wiskott Aldrich syndrome
Immunosuppression after kidney transplantation

13. Complements are...
DM type I
Soluble C3 spontaneously hydrolyzes spontaneously to C3b and opsonizes microbial and host cell surfaces and accumulates on surfaces; C3b activates C5 convertase which leads to MAC activation
acute phase reactants
Barrel hoop basement membrane fenestrations

14. What are the two signals required for Th1 cells? what happens after then activated?
secondary
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
IgG

15. The secondary follicles have __________; primary follicles are dense
Negative nitroblue tetrazolium reduction test
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
pale central germinal centers
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

16. What are the autoantibodies for pernicious anemia?
Anti IF
Alternative splicing of mRNA
Liver! (they are proteins circulating in the blood)
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

17. What lymph node drains the rectum (above the pectinate line)?
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
Internal iliac
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

18. Name the three opsonins
Superficial inguinal
CRP - C3b - IgM
Fc
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

19. what ensure that a memory response is generated?
Influenza; antigenic shift; antigenic drift
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
If there is class switching and plasma cell production (that is when memory cells are produced)

20. Give an example of someone who could get hyperacute transplant rejection.
Cyclosporine - OKT3
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Previous transfusion; pregnant woman whose fetus had paternal antigens
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

21. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
MHC class molecules bind to KIRS or CD94 to prevent killing
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
IL 4 - 5 - 10 - 6
...

22. 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 )
IgM and IgA
Yes
Negative nitroblue tetrazolium reduction test

23. What are the major functions of Antibodies?
No because no peptide fragment!
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
IgAs in mothers breast milk!

24. What are the three types of lymphocytes?
B - T - and NK 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
type four
Influenza; antigenic shift; antigenic drift

25. What does interferon gamma do to be antiviral?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Superficial inguinal
Increases expression of MHC I and MHC II and also activates NK cells
TGF beta and IL 10

26. What is chronic mucocutaneous candidiasis d/t?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
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
RNA segment reassortment

27. which type of immunity is slow but long lasting? as opposed to...
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
Fc
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Active; passive - fast but short half life (3 weeks!)

28. What are the autoantibodies for myasthenia gravis?
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Anti Ach receptor
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

29. What can cause a lymph node enlargement?
Local infection/inflammation; infection of the ln itself; metastasis
cannot cross placenta
False! B cell class switching requires a second signal
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

30. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
A chemotactic factor for neutrophils
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

31. What are C1 - C2 - C3 - C4 important for?
Liver! (they are proteins circulating in the blood)
Viral neutralization of igM and IgG!
False! B cell class switching requires a second signal
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

32. which cytokine inhibits TH2 cells? secreted by who?
Axillary
not Ab mediated
Alternative splicing of mRNA
Interferon gamma; Th1

33. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
When you select for which MHC it will have; take out the lymphs that self react
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
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
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!

34. What are the PALS?
Interferon gamma; Th1
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Superficial inguinal
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

35. What are some sinopulmonary infections?
Carbohydrate
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Sinusitis - otitis media - pneumonia
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

36. The Fc region is found on the...
By transcytosis
carboxy terminal
A - B - C; all the D's
Its a serine protease that activates apoptosis; NK and CD8

37. What bugs can actually infect the lymph node itself?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
except hyperacute
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
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

38. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Superior mesenteric
2 heavy chains and two light chains

39. What does it mean if there are igM in the serum at birth?
All MHC 1/CD8
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
IL 1 and IL 6

40. Monomer in circulation - ___ when secreted
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!
dimer
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Aut. Dominant; C1 esterase inhibitor deficiency resulting in continued C1 which results in increased C2 and C4 cleavage products which have anaphyltoxic activity and result in swelling of face and oropharynx

41. Which MHC presents intracellular peptides? how so?
In the germinal center of secondary follicles (In the paler center)
MHC I; from RER with help of the B2 microglobulin
Remove encapsulated bacateria
Negative nitroblue tetrazolium reduction test

42. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Superficial inguinal
Activate macrophages
Edema and necrosis in that region
Axillary

43. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
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
Activates cytotoxic CD 8 T cells as second signal

44. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
Immunosuppression after kidney transplantation
IL 5
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

45. How fast does it occur?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
CD21 on B cells (although there is T cell lymphocytosis in EBV)
The patient could become cyanotic in the OR!
Delayed type hypersensitivity

46. Which disease is associated with B8?
IL 15; IL 12 - interferon Beta and interferon alpha
NK cells
Graves
Glycoproteins; HLA

47. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Influenza; antigenic shift; antigenic drift
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
Anti Jo -1
TGF beta and IL 10

48. Which helper T cells' development is induced by IL 4? IL 12?
Its main effect is a defect in Ab opsonization for killing
Th2; Th1
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Superficial inguinal

49. How is the antigen loaded onto a MHC II?
MHC I; from RER with help of the B2 microglobulin
Influenza; antigenic shift; antigenic drift
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
C5a

50. What are the autoantibodies for Mixed connective tissue disease?
IgG
Anti U1 RNP (ribonucleoprotein)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
...