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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 lymph node drains the testes?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Para aortic
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

2. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

3. What does CD16 on NK cells do?
Bind FcG for antibody dependent cellular cytotoxicity
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
CRP - C3b - IgM
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

4. What happens in a deficiency of C3?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
IL 15; IL 12 - interferon Beta and interferon alpha
Pernicious Anemia and Hashimotos
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

5. What is the clinical use for azathioprine?
Hemochromatosis
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
...
Edema and necrosis in that region

6. So antibodies are the effectors for the humoral response. List some of their functions.
Antibody mediated cytotoxicity; either complement dependent or complement independent
IgM and IgA
Pernicious Anemia and Hashimotos
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

7. when can graft versus host disease? What is the result?
CRP - C3b - IgM
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
Severe pyogenic infections early in life
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE

8. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
dimer
B - T - and NK cells
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

9. To what portion of the Antibody do the complements bind?
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
Fc
Antihistone
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

10. which antibody activate mast cells - basophils - and eosinophils?
T
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
except hyperacute
IgE

11. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
T cell dysfunction
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

12. What are the autoantibodies for systemic sclerosis?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Anti topoisomerase

13. Which diseases are associated with DR5?
acute phase reactants
Pernicious Anemia and Hashimotos
Acts as second signal on B cells to induce class switching to IgE and IgG
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

14. other than C3a - what other complement acts as an anaphyloxin?
Activates Th1 helper cells; Macrophages
Antidesmoglein
C5a
Wiskott Aldrich syndrome

15. other than eat and bite RBCs what else do Macrophages of spleen do>
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
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 :(
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Remove encapsulated bacateria

16. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
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
Cyclosporine - OKT3
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

17. What are the two signals required for B cell class switching? Which is the second signal?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Hemochromatosis
active complement pathway
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

18. What are the main symptoms of T cell immunodeficiencies?
In the germinal center of secondary follicles (In the paler center)
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

19. What lymph node drains the sigmoid colon?
Antidote for digoxin intoxication
DM type I and RA
Inferior mesenteric
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

20. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
Th2; Th1
Cyclosporine - OKT3
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Negative selection

21. What lymph node drains the rectum (above the pectinate line)?
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Immunosuppression after kidney transplantation
IgG
Internal iliac

22. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
Cyclosporine - OKT3
Cells that stil have weird parts of their membrane that macrophages usually bite off
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
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

23. which B and T cell disorder presents with specifically low IgM?
Wiskott Aldrich syndrome
CD21 on B cells (although there is T cell lymphocytosis in EBV)
IgG
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

24. What kinds of receptors activate innate immunity?
Wiskott Aldrich syndrome
dimer
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
TLR ad nuclear receptors

25. 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 )
Superficial inguinal
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
IgG

26. What are the autoantibodies for hashimotos?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
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
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
Antimicrosomal and antithyroglobulin

27. Only the _______ contribute to the Fc region
heavy chains
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Cyclosporine - OKT3
Chronic granulomatous disease

28. What lymph node drains the duodenum - jejunum?
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!
Superior mesenteric
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

29. What is a factor that is a predictor for a bad transplantation?
NK cells
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Receiving preformed Antibodies
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

30. What is the autoantibody for SLE that is nonspecific? Specific?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
No because no peptide fragment!
Superficial inguinal
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 :(

31. what cytokine does basophils secrete?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
IL 4
Antihistone
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

32. What is the main function of IL 8?
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!
A chemotactic factor for neutrophils
secondary
The patient could become cyanotic in the OR!

33. What does IL 5 do?
Glycoproteins; HLA
IgM
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
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

34. What is digoxin immune Fab used for?
Th cells fail to produce interferon gamma; a lot of IgE
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
Antidote for digoxin intoxication
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

35. IgE has the ___________ in the serum
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
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
lowest concentration
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

36. What is oprelevkin? and What is it used for?
Recom IL 11; thrombocytopenia
Remove encapsulated bacateria
except hyperacute
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 :(

37. What is the pathology of acute transplant rejection? is it reversible?
Delayed type hypersensitivity
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
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

38. What are the autoantibodies for polymyositis and dermatomyositis?
Anti glutamate carboxylase and anti insulin
Anti Jo -1
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
MS

39. What is the mode of inheritance of Chediak Higashi syndrome? What is the disease d/t? What does it result in? What is the presentation?
Superficial inguinal
pathogenesis
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

40. In general What are T cells good for?
Superficial inguinal
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Anti viral and anti tumor
Barrel hoop basement membrane fenestrations

41. What lymph node drains the anal canal (below the pectinate line)?
Superficial inguinal
Recom IL 11; thrombocytopenia
RNA segment reassortment
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

42. are Th cells involved in trapping of antigens of endotoxin/LPS?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
No because no peptide fragment!
CROSS LINK Beta region on TCR of CD4 cells to the MHC class II on APCs this results in uncoordinated release of Interferon gamma from CD4 Th1 cells and subsequent release of IL1 - IL6 and TNF alpha from Macrophages --> toxic shock syndrome; s. pyogen

43. What is the mechanism for sirolimus? what else it known as?
IgM
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
Th cells fail to produce interferon gamma; a lot of IgE
NK cells

44. What are the three types of lymphocytes?
Anti IF
B - T - and NK cells
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Its a serine protease that activates apoptosis; NK and CD8

45. The ______ in the BM are DN - the DP are in the cortex of thymus
Internal iliac
T cell precursor
Severe pyogenic infections early in life
A chemotactic factor for neutrophils

46. what prevents NK cells from killing normal cells if their default is to kill?
MHC class molecules bind to KIRS or CD94 to prevent killing
Fc
Anti alpha subunit 3 of collagen on type IV bm
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

47. Give an example of someone who could get hyperacute transplant rejection.
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Humoral
Previous transfusion; pregnant woman whose fetus had paternal antigens

48. Name two endogenous pyrogens
IL 1 and IL 6
Thrombocytopenia
False! B cell class switching requires a second signal
Hereditary angioedema; PNH

49. In thymic development - What is the positive selection? negative selections?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
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
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
When you select for which MHC it will have; take out the lymphs that self react

50. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
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
Hemochromatosis
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP