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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 pathology in hyperacute transplant rejection?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Histamine; post capillary venules - vasodilation
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

2. What does IL 2 do?
Th cells fail to produce interferon gamma; a lot of IgE
Activates cytotoxic CD 8 T cells as 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
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

3. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Rheumatic arthritis
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

4. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Rheumatic arthritis
Sinusitis - otitis media - pneumonia
pathogenesis

5. What is Aldesleukin? What is it used for
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Cytokine IL 10 secreted by Th2
IgG
A recomb cytokine of IL 2; RCC and metastatic melanoma

6. Which antibody mediates immunity to worms? how?
IgE; by activating eosinophils
Hereditary angioedema; PNH
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Cytokine IL 10 secreted by Th2

7. Which is the main antibody in the delayed or secondary response to an antigen?
type four
Anti Jo -1
DM type I and RA
IgG

8. What is the main function of TNF alpha? How does it do this?
Superficial inguinal
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
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

9. What is three common causes of severe combined immunodef? What is the result of all three?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
acute phase reactants
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

10. what secretes IL 4?
Anti topoisomerase
Stimulate the liver to release acute phase reactants
Antimicrosomal and antithyroglobulin
Basophils! THey want IG E class switch!

11. What is an example of a parasite showing antigenic variation?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Negative selection
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

12. The idiotype; the Fc portion determines the...
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
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)
isotype
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

13. describe the classic complement pathway.
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
IL 4
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

14. What happens in a secondary follicle?
Kill them because they have CD16 on them that recognize the FcG portion
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
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
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation

15. What bugs can actually infect the lymph node itself?
IL 4
Anti topoisomerase
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

16. IgM can exist as a _______ also
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
pentamer
Anemias (esp due to renal failure)
type four

17. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
Immunosuppression after kidney transplantation
Anti Jo -1
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

18. So antibodies are the effectors for the humoral response. List some of their functions.
IgG
Humoral
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

19. Which disease is associated with HLA A3?
Hemochromatosis
False! B cell class switching requires a second signal
T cell precursor
Barrel hoop basement membrane fenestrations

20. What is the toxicity of muromonab?
Wiskott Aldrich syndrome
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

21. What is the presentation of Brutons agammaglobulinemia?
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
Internal iliac
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

22. What is oprelevkin? and What is it used for?
Rheumatic arthritis
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Recom IL 11; thrombocytopenia
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)

23. What does IgA pick up from epithelial cells before being secreted?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Activate macrophages
Secretory component
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

24. What are the autoantibodies for pemphigus bulgaris?
IL 4
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
Antidesmoglein
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

25. What is the clinical use for sirolimus? what should you combine it with?
Internal iliac
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
heavy chains
Secretory component

26. What is the main function of interferons?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Increases expression of MHC I and MHC II and also activates NK cells
IgA
Local infection/inflammation; infection of the ln itself; metastasis

27. Other than stimulating fever - what else does IL 6 do?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Cells that stil have weird parts of their membrane that macrophages usually bite off
Negative nitroblue tetrazolium reduction test
Stimulate the liver to release acute phase reactants

28. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
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
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Carbohydrate

29. Complements are...
active complement pathway
heavy chains
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
acute phase reactants

30. which antibody is involved in the primary response or immediate response to an antigen?
IgM
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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
Liver! (they are proteins circulating in the blood)

31. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
TNF alpha and IL1
Severe pyogenic infections early in life
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Increases expression of MHC I and MHC II and also activates NK cells

32. Name two endogenous pyrogens
pale central germinal centers
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
IL 1 and IL 6

33. What is the common variable immunodeficiency ? How is it different from Brutons?
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 II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
MHC II - B7
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

34. What are the two signals required for T cells? what happens after?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Daclizumab; prevent ACUTE rejection of renal transplant
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Axillary

35. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
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
A j chain
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 :(
Superficial inguinal

36. What is the pathogenesis of chronic transplant rejection? When does it occur? is it reversible?
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 :(
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
secondary
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

37. What are some catalase positive organisms?
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
T cell precursor
S. aureus - E. Coli - aspergillus
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

38. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
CD56
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
IL 4
False! B cell class switching requires a second signal

39. give an example of how influenza does a major antigenic shift.
Edema and necrosis in that region
Th cells fail to produce interferon gamma; a lot of IgE
IL 4 - 5 - 10 - 6
RNA segment reassortment

40. What are the autoantibodies for hashimotos?
The patient could become cyanotic in the OR!
MHC I - CD16 - CD56
except hyperacute
Antimicrosomal and antithyroglobulin

41. What is the treatment of acute transplant rejection?
Immunoflourescent staining of tissue biopsies
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Cyclosporine - OKT3
Inferior mesenteric

42. What is the cause of thymic aplasia? What is its presentation? What are the labs?
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
A - B - C; all the D's
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
...

43. What is the main function of IL 8?
Anti smooth muscle
A chemotactic factor for neutrophils
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

44. what bacteria are a splenectomy patient most susceptible to? why?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Interferon gamma and IL 2

45. What is recomb beta interferon used for?
Tetanus - Botulinum - HBV - Rabies
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Active; passive - fast but short half life (3 weeks!)
MS

46. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
Basophils! THey want IG E class switch!
active complement pathway
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
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

47. What are MHC's necessary for? By themselves?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
T cell activation; no with CD 4 or CD 8
2 heavy chains and two light chains
NK cells

48. What is the presentation of hyperIgM syndrome?
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)
Not thymus - BM
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 :(
Severe pyogenic infections early in life

49. What lymph node drains the scrotum?
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
Activate macrophages
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Superficial inguinal

50. what results in symptoms of shock in an acute hemolytic transfusion reaction?
C5a
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Basophils! THey want IG E class switch!
Th2; Th1