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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. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
Superficial inguinal
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
T cell and antibody mediated vascular damage due to MHC non self being recognized as self by self lymphocytes and resulting in attack of the foreign antigens it presents (all of them); months to years after; no :(

2. What is the late phase reaction of anaphylaxis allergy? what mediates it?
Barrel hoop basement membrane fenestrations
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)
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
For some reason a mature naive B lymphocyte got away from tolerance and the result was a production an Ab on its surface with an Fab region that recognized the alpha 3 collagen subunit on the BM as non self. It then gets activated by a Th2 cell (enti

3. Which is the main antibody that provides passive immunity to infants?
IgG
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Kill them because they have CD16 on them that recognize the FcG portion
B - T - and NK cells

4. what happens in a deficiency of C1 esterase inhibitor? DAF?
Hereditary angioedema; PNH
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Negative!
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

5. IgM can exist as a _______ also
Fab portion
Liver! (they are proteins circulating in the blood)
pentamer
Superficial inguinal

6. What are the autoantibodies for hashimotos?
Antimicrosomal and antithyroglobulin
Anti alpha subunit 3 of collagen on type IV bm
Th2; Th1
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

7. What does IL 10 do? who is secreted by?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Negative nitroblue tetrazolium reduction test
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
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

8. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
For some reason a mature naive B lymphocyte got away from tolerance and the result was a production an Ab on its surface with an Fab region that recognized the alpha 3 collagen subunit on the BM as non self. It then gets activated by a Th2 cell (enti
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
A chemotactic factor for neutrophils
Type IV

9. What is the most common example of passive immunity?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
IgAs in mothers breast milk!
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
TGF beta and IL 10

10. What is the main function of interferons?
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
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Anti TSh receptor
cannot cross placenta

11. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Influenza; antigenic shift; antigenic drift
Hemochromatosis
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

12. Name 5 ways Antibody diversity is generated?
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
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Receiving preformed Antibodies
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

13. What are howell jolly bodies?
Interferon gamma; Th1
S. aureus - E. Coli - aspergillus
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!

14. What are the two signals required for Th1 cells? what happens after then activated?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
active complement pathway
The red pulp of the spleen its where the vasculature channels go through and interact with the parenchyma of the spleen (has macrophages) which empty in the sinuses; they are both encapsulated (with trabeculae) secondary lymphoid organs that trap ant

15. Name the three opsonins
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Anti viral and anti tumor
CRP - C3b - IgM
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils

16. What is the main function of IL 8?
Type IV
Axillary
A chemotactic factor for neutrophils
Cells that stil have weird parts of their membrane that macrophages usually bite off

17. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
No because no peptide fragment!

18. what ensure that a memory response is generated?
If there is class switching and plasma cell production (that is when memory cells are produced)
Cyclosporine - OKT3
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)

19. What are the autoantibodies for autoimmune hepatitis?
active complement pathway
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
CD56
Anti smooth muscle

20. What is chronic mucocutaneous candidiasis d/t?
IgM and IgA
T cell dysfunction
Cross link
The red pulp of the spleen its where the vasculature channels go through and interact with the parenchyma of the spleen (has macrophages) which empty in the sinuses; they are both encapsulated (with trabeculae) secondary lymphoid organs that trap ant

21. Only the _______ contribute to the Fc region
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
heavy chains
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Yes

22. Describe the capsular structure of a lymph node; What are the functions of the LN?
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
secondary
CRP - C3b - IgM
A - B - C; all the D's

23. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Tetanus - Botulinum - HBV - Rabies
Activates cytotoxic CD 8 T cells as second signal
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

24. What is the treatment of acute transplant rejection?
First a B cell gets sensitized to an allergen - after sensitization - it gets induce by Th2 secreting IL4 to class switch from IgM to IgE - next time blood stream is exposed to allergen these antigens cross like IgEs on mast cells and result in chemi
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
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Cyclosporine - OKT3

25. In thymic development - What is the positive selection? negative selections?
When you select for which MHC it will have; take out the lymphs that self react
Anti alpha subunit 3 of collagen on type IV bm
Anti TSh receptor
A chemotactic factor for neutrophils

26. What type of side chains are found on Fc region of an antibody?
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
Carbohydrate
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
B - T - and NK cells

27. What does IL 2 do?
Anti glutamate carboxylase and anti insulin
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
Activates cytotoxic CD 8 T cells as second signal
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

28. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
TNF alpha and IL1
For some reason a mature naive B lymphocyte got away from tolerance and the result was a production an Ab on its surface with an Fab region that recognized the alpha 3 collagen subunit on the BM as non self. It then gets activated by a Th2 cell (enti
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Negative!

29. For which toxins are preformed antibodies (passive) given?
RNA segment reassortment
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Type IV
Tetanus - Botulinum - HBV - Rabies

30. what secretes IL 4?
Hemochromatosis
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Basophils! THey want IG E class switch!
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

31. What bugs can actually infect the lymph node itself?
All MHC 1/CD8
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
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

32. What is the white pulp of the spleen?
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
neutrophilia!
Anti U1 RNP (ribonucleoprotein)
A chemotactic factor for neutrophils

33. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
Activate macrophages
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
A j chain
Anti TSh receptor

34. What is the pathogenesis of a candida skin test?
All MHC 1/CD8
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Delayed type hypersensitivity
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

35. What is the main function of TNF alpha? How does it do this?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Receiving preformed Antibodies
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

36. What are the autoantibodies for graves?
Anti TSh receptor
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
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

37. where do NK cells develop?
neutrophilia!
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Not thymus - BM
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

38. What is anergy? why does this occur?
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
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
CRP - C3b - IgM

39. which cytokine inhibits TH2 cells? secreted by who?
Interferon gamma; Th1
Influenza; antigenic shift; antigenic drift
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
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

40. What are the autoantibodies for systemic sclerosis?
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Anti topoisomerase

41. What lymph node drains the stomach?
Celiac
Hemochromatosis
A - B - C; all the D's
Anti smooth muscle

42. What is the toxicity of muromonab?
Negative selection
Anti U1 RNP (ribonucleoprotein)
Negative nitroblue tetrazolium reduction test
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

43. What lymph node drains the lateral side of the dorsum of the foot?
First a B cell gets sensitized to an allergen - after sensitization - it gets induce by Th2 secreting IL4 to class switch from IgM to IgE - next time blood stream is exposed to allergen these antigens cross like IgEs on mast cells and result in chemi
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
S. aureus - E. Coli - aspergillus
Popliteal

44. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Remove encapsulated bacateria
Influenza; antigenic shift; antigenic drift
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
CRP - C3b - IgM

45. Which disease is associated with DR3?
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
DM type I
Basophils! THey want IG E class switch!
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

46. What are the function of B cells?
The red pulp of the spleen its where the vasculature channels go through and interact with the parenchyma of the spleen (has macrophages) which empty in the sinuses; they are both encapsulated (with trabeculae) secondary lymphoid organs that trap ant
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
IgM
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

47. What is epo used for?
IgAs in mothers breast milk!
Axillary
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Anemias (esp due to renal failure)

48. What is a factor that is a predictor for a bad transplantation?
Fc
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Anti alpha subunit 3 of collagen on type IV bm

49. If an antigen lacks a peptide component How does the adaptive immunity attack it? What type of response is this called. give an example of bugs that do this. what implications does this have on splenectomy?
Stimulate the liver to release acute phase reactants
Steroid responsive nephrotic syndrome
This means that MHC can not recognize it and thus will not be phagocytosed. The humoral response rescues - IgM is the primary response attack. Since there is no class switching (without MHC activation no CD40 L and interleukins to activate!) then the
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

50. are Th cells involved in trapping of antigens of endotoxin/LPS?
Severe pyogenic infections early in life
RNA segment reassortment
No because no peptide fragment!
Anti glutamate carboxylase and anti insulin