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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 cytokines do macrophages release? who else can secrete IL 6? IL 12?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
IL 3; supports growth and differentiation of bone marrow stem cells
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Its main effect is a defect in Ab opsonization for killing

2. What is colostrum?
IL 5
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
The igA found in breast milk
CD21 on B cells (although there is T cell lymphocytosis in EBV)

3. What lymph node drains the testes?
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
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
Para aortic
carboxy terminal

4. Type IV hypersensitivity is i...
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
not Ab mediated
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Lymphocytes

5. What lymph node drains the upper limb?
Not thymus - BM
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
MHC I; from RER with help of the B2 microglobulin
Axillary

6. 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?
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
RNA segment reassortment

7. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
Kill them because they have CD16 on them that recognize the FcG portion
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Alternative splicing of mRNA
Interferon gamma; Th1

8. What is the receptor for EBV? On what cells is that located?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Secretory component

9. What does IL 2 do?
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
MHC I - CD16 - CD56
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

10. can igG cross the placenta?
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
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Yes

11. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Histamine; post capillary venules - vasodilation
Th cells fail to produce interferon gamma; a lot of IgE
IgAs in mothers breast milk!
Receiving preformed Antibodies

12. is IgM an opsonizer?
Paracortex
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
T cell precursor
Negative!

13. What is the autoantibody for SLE that is nonspecific? Specific?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Interferon gamma and IL 2
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Immunoflourescent staining of tissue biopsies

14. Type Iv hypersensitivity is...
delayed!
IgM and IgG
Axillary
By transcytosis

15. What is passive immunity?
Anti smooth muscle
Receiving preformed Antibodies
not Ab mediated
Superficial inguinal

16. To what portion of the Antibody do the complements bind?
Th2; Th1
IgM and IgD
IgAs in mothers breast milk!
Fc

17. What is epo used for?
Active; passive - fast but short half life (3 weeks!)
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
B - T - and NK cells
Anemias (esp due to renal failure)

18. How is i Th1 helper cell inhibited?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Cytokine IL 10 secreted by Th2
Increases expression of MHC I and MHC II and also activates NK cells
heavy chains

19. What are C1 - C2 - C3 - C4 important for?
Viral neutralization of igM and IgG!
IgE; by activating eosinophils
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

20. What are the two signals required for B cell class switching? Which is the second signal?
MHC II - B7
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
IgA
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

21. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
TNF alpha and IL1

22. What are the three types of APCs?
Macrophages - Dendritic cells - B cells
Active; passive - fast but short half life (3 weeks!)
IgG
active complement pathway

23. What does Interferon alpha and beta do? how?
By transcytosis
A j chain
Graves
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

24. What are the labs in brutons agammaglobulinemia?
Alternative splicing of mRNA
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

25. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
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
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Histamine; post capillary venules - vasodilation
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

26. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
Celiac
...
Immunosuppression after kidney transplantation
Immunoflourescent staining of tissue biopsies

27. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
Increases expression of MHC I and MHC II and also activates NK cells
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
SP infections
Cross link

28. What is the clinical use for azathioprine?
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
Cells that stil have weird parts of their membrane that macrophages usually bite off
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
...

29. T/F B cells do not require a second signal
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Barrel hoop basement membrane fenestrations
False! B cell class switching requires a second signal
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class

30. which antibody is involved in the primary response or immediate response to an antigen?
type four
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
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)
IgM

31. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
False! B cell class switching requires a second signal
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
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

32. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
In the germinal center of secondary follicles (In the paler center)
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)

33. Describe the capsular structure of a lymph node; What are the functions of the LN?
MHC I - CD16 - CD56
Superficial inguinal
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
Inferior mesenteric

34. What lymph node drains the stomach?
Celiac
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Liver! (they are proteins circulating in the blood)
Anti glutamate carboxylase and anti insulin

35. what characterizes an arthus reaction?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Edema and necrosis in that region
MS - hay fever - SLE - goodpastures
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

36. Which MHC presents intracellular peptides? how so?
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
MS - hay fever - SLE - goodpastures
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 I; from RER with help of the B2 microglobulin

37. What cytokines to Th2 secrete?
IL 4 - 5 - 10 - 6
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Interferon gamma and IL 2
Fab portion

38. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
isotype
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
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
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

39. what cell surface proteins are on all APCs?
MHC II - B7
MHC class molecules bind to KIRS or CD94 to prevent killing
...
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

40. What bugs can actually infect the lymph node itself?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Secretory component
Acts as second signal on B cells to induce class switching to IgE and IgG
Superior mesenteric

41. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
Macrophages - Dendritic cells - B cells
Acts as second signal on B cells to induce class switching to IgE and IgG
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
lowest concentration

42. What is immune complex disease? give an example.
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Negative!
Negative selection
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

43. What is the main function of IL 12? other than macrophages who else can release IL 12?
T cell activation; no with CD 4 or CD 8
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

44. give an example of how influenza does a major antigenic shift.
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
RNA segment reassortment
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Pernicious Anemia and Hashimotos

45. What lymph node drains the lateral side of the dorsum of the foot?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Popliteal
Type IV
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

46. 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?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Popliteal

47. ________ regulate the cell mediated response.
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
Humoral
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
Increases expression of MHC I and MHC II and also activates NK cells

48. What do multimeric antibodies require for assembly?
A j chain
False! B cell class switching requires a second signal
IgM and IgD
MS

49. 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 )
IL 3; supports growth and differentiation of bone marrow stem cells
MS
Superficial inguinal

50. What is the toxicity of muromonab?
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Superficial inguinal