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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. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Yes
A recomb cytokine of IL 2; RCC and metastatic melanoma

2. 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
T cell precursor
A chemotactic factor for neutrophils
Give a vaccine with a peptide comp from it that the cell mediated immunity otherwise cant get to! like h.influenzae vaccine. then class switching and memory response can occur

3. __________ are a part of the innate system.
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
DM type I and RA
Carbohydrate
NK cells

4. Describe the capsular structure of a lymph node; What are the functions of the LN?
Lymphocytes
TNF alpha and IL1
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
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

5. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
Antihistone
Closed circuit where go directly to veins and open where squeeze out of capillary sinusoids and interact with either PALS or with macrophages in the cords of Billroth (for antigen immune function or for blood cleaning or for both) and squeeze back in
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

6. which antibodies prevent antigens from binding mucosal surfaces?
T cell activation; no with CD 4 or CD 8
Anemias (esp due to renal failure)
All MHC 1/CD8
IgA

7. The two heavy chains of an antibody contribute to the...
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
RNA segment reassortment
Fab portion

8. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
Graves
IgAs in mothers breast milk!
Antibody mediated cytotoxicity; either complement dependent or complement independent
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

9. What is serum sickness? give an example.
Interferon gamma; Th1
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
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
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

10. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
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
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
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

11. The MALT/GALT are not...
Complement activation (active in both)
pale central germinal centers
encapsulated
T cell precursor

12. What are the three types of lymphocytes?
except hyperacute
B - T - and NK cells
Tetanus - Botulinum - HBV - Rabies
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

13. What type of fenestrations are found in the red pulp of the spleen?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Receiving preformed Antibodies
Barrel hoop basement membrane fenestrations
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

14. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
...
No because no peptide fragment!
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils

15. What are the autoantibodies for systemic sclerosis?
dimer
Give a vaccine with a peptide comp from it that the cell mediated immunity otherwise cant get to! like h.influenzae vaccine. then class switching and memory response can occur
By transcytosis
Anti topoisomerase

16. What lymph node drains the rectum (above the pectinate line)?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Anti viral and anti tumor
Graves
Internal iliac

17. What does IL 2 do?
IL 3; supports growth and differentiation of bone marrow stem cells
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Activates cytotoxic CD 8 T cells as second signal
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells

18. is IgM an opsonizer?
Complement activation (active in both)
Recom IL 11; thrombocytopenia
Cross link
Negative!

19. What cytokines are released by Th1 cells?
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
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Interferon gamma and IL 2
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

20. What does interferon gamma do? What two type of cells does it attack mostly?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Anemias (esp due to renal failure)
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
The patient could become cyanotic in the OR!

21. what cell surface proteins are on all APCs?
MHC II - B7
MS
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

22. which antibody is involved in the primary response or immediate response to an antigen?
T
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
IgM
Th2; Th1

23. What is an example of a parasite showing antigenic variation?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Activate macrophages
Chronic granulomatous disease
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

24. Which diseases are associated with DR2?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
MS - hay fever - SLE - goodpastures
Pernicious Anemia and Hashimotos
CD56

25. What are the autoantibodies for hashimotos?
Antibody mediated cytotoxicity; either complement dependent or complement independent
When you select for which MHC it will have; take out the lymphs that self react
Antimicrosomal and antithyroglobulin
Cells that stil have weird parts of their membrane that macrophages usually bite off

26. What are the main symptoms of T cell immunodeficiencies?
except hyperacute
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Anti IF
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

27. What is the main cytokine released by T cells? What does it do
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
IL 3; supports growth and differentiation of bone marrow stem cells
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

28. What are some 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
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Basophils! THey want IG E class switch!

29. What is the clinical use for azathioprine?
...
Alternative splicing of mRNA
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Active; passive - fast but short half life (3 weeks!)

30. What links the adaptive and innate immunity?
MS - hay fever - SLE - goodpastures
Complement activation (active in both)
lowest concentration
Secretory component

31. What do mature naive B lymphocytes express?
RNA segment reassortment
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
IgA
IgM and IgD

32. What is passive immunity?
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
Receiving preformed Antibodies
Anti IF
Rheumatic arthritis

33. which antibody activate mast cells - basophils - and eosinophils?
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
IgE
Give a vaccine with a peptide comp from it that the cell mediated immunity otherwise cant get to! like h.influenzae vaccine. then class switching and memory response can occur
IgM and IgA

34. What are the autoantibodies for Mixed connective tissue disease?
Anti U1 RNP (ribonucleoprotein)
IgG
Liver! (they are proteins circulating in the blood)
Anti viral and anti tumor

35. What is the receptor for EBV? On what cells is that located?
opsonizes
type four
CD21 on B cells (although there is T cell lymphocytosis in EBV)
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

36. What portion of the lymph node is not well developed in DiGeorge Syndrome?
Axillary
Popliteal
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 :(
Paracortex

37. What is the most common selective Ig deficiency? What is the presentation?
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
IgAs in mothers breast milk!
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Basophils! THey want IG E class switch!

38. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
opsonizes
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
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

39. What are the labs in brutons agammaglobulinemia?
NK cells
Complement activation (active in both)
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class

40. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
Bind FcG for antibody dependent cellular cytotoxicity
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

41. what will NK cells do to cells covered in IgG Ab? why?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
S. aureus - E. Coli - aspergillus
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
Kill them because they have CD16 on them that recognize the FcG portion

42. Which disease is associated withB B27?
Anti smooth muscle
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Fab portion
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

43. What is recomb beta interferon 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
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
MS
Stimulate the liver to release acute phase reactants

44. What are the T cell functions?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
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!

45. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Pernicious Anemia and Hashimotos
Its main effect is a defect in Ab opsonization for killing
IL 3; supports growth and differentiation of bone marrow stem cells

46. What lymph node drains the sigmoid colon?
Negative!
By transcytosis
except hyperacute
Inferior mesenteric

47. What are the sinusoids of the spleen? What is the difference between a spleen and a lymph node?
pentamer
Lymphocytes
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
CD21 on B cells (although there is T cell lymphocytosis in EBV)

48. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
False! B cell class switching requires a second signal
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

49. What is the pathology of acute transplant rejection? is it reversible?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
No because no peptide fragment!
Superficial inguinal
Remove encapsulated bacateria

50. How do you test for chronic granulomatous disease?
Th2; Th1
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
IgM and IgA
Negative nitroblue tetrazolium reduction test