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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.
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1. IgG...
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
opsonizes
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

2. What are the autoantibodies for sjorgens syndrome?
heavy chains
2 heavy chains and two light chains
IL 5
Anti SS- A (anti RO) and Anti SS- B

3. Describe the capsular structure of a lymph node; What are the functions of the LN?
Lymphocytes
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Negative selection
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

4. What is the clinical use of Muromonab?
Antimicrosomal and antithyroglobulin
Immunosuppression after kidney transplantation
...
Hemochromatosis

5. How is sirolimus different from tacrolimus?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Previous transfusion; pregnant woman whose fetus had paternal antigens
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

6. Only the _______ contribute to the Fc region
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
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
heavy chains
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

7. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
DM type I and RA
Not thymus - 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

8. what cell surface proteins are on all APCs?
MHC II - B7
Anti Ach receptor
Activates Th1 helper cells; Macrophages
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)

9. Which diseases are associated with DR5?
Pernicious Anemia and Hashimotos
Yes
Activate macrophages
Anti smooth muscle

10. where are complements produced?
Axillary
Anti TSh receptor
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Liver! (they are proteins circulating in the blood)

11. What does IgA pick up from epithelial cells before being secreted?
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
Secretory component
Previous transfusion; pregnant woman whose fetus had paternal antigens
Superficial inguinal

12. What are the autoantibodies for graves?
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
Anti TSh receptor
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Increases expression of MHC I and MHC II and also activates NK cells

13. in which immunodef order do you see a lot of pus? no pus?
IL 15; IL 12 - interferon Beta and interferon alpha
IL 4
secondary
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

14. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Histamine; post capillary venules - vasodilation
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

15. what characterizes an arthus reaction?
IL 4
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Edema and necrosis in that region
S. aureus - E. Coli - aspergillus

16. What are the labs in brutons agammaglobulinemia?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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
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
NK cells

17. What are the cell surface proteins for Macrophages? which two are for opsonins?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
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
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Graves

18. describe the pathogenesis of delayed type IV hypersensitivity
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
T
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)

19. What is recomb alpha interferon used for?
IL 15; IL 12 - interferon Beta and interferon alpha
pentamer
False! B cell class switching requires a second signal
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

20. What is the main cytokine that activates eosinophils?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Anti Ach receptor
Anti SS- A (anti RO) and Anti SS- B
IL 5

21. What bugs can actually infect the lymph node itself?
Para aortic
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

22. What is the main function of IL 12? other than macrophages who else can release IL 12?
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
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
IgG
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

23. What lymph node drains the thigh?
Internal iliac
Superficial inguinal
A recomb cytokine of IL 2; RCC and metastatic melanoma
Severe pyogenic infections early in life

24. What is the defect in hyper IgM syndrome? What are the lab results?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
SP infections
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

25. Which disease is associated with DR7?
Chronic granulomatous disease
IgM and IgG
Celiac
Steroid responsive nephrotic syndrome

26. 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
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
IgM
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

27. IgM can exist as a _______ also
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
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
pentamer
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

28. What is muromonab - CD3 (OKT3)
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
Immunoflourescent staining of tissue biopsies
Superficial inguinal
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells

29. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
IL 5
SP infections
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

30. Describe the Mannose Lectin pathway
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Antidesmoglein
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

31. What does IL 5 do?
A recomb cytokine of IL 2; RCC and metastatic melanoma
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils

32. What are the autoantibodies for other vasculitides?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Secretory component
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Recom IL 11; thrombocytopenia

33. What are some catalase positive organisms?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
S. aureus - E. Coli - aspergillus
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Receiving preformed Antibodies

34. The alternative pathway is the only constutively...
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Axillary
Antihistone
active complement pathway

35. Describe the complement independent Type II hypersenstivity reaction. Give an example.
In the germinal center of secondary follicles (In the paler center)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
IL 5
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

36. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
A recomb cytokine of IL 2; RCC and metastatic melanoma
No because no peptide fragment!
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

37. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Histamine; post capillary venules - vasodilation
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!
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

38. What do multimeric antibodies require for assembly?
Cells that stil have weird parts of their membrane that macrophages usually bite off
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
A j chain

39. So antibodies are the effectors for the humoral response. List some of their functions.
Negative nitroblue tetrazolium reduction test
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Humoral
Anemias (esp due to renal failure)

40. What is anergy? why does this occur?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Type II hypersensitivity - complement dependent resulting in phagocytosis of RBCs coated with C3b by fixed macrophages in the spleen; Group O mother has anti A - B - IgG Abs that cross placenta and attach to fetal blood group A or B RBCs
IgM and IgD
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

41. Type Iv hypersensitivity is...
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
delayed!
Anti glutamate carboxylase and anti insulin
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

42. what cell surface marker is used for NK cells as it is unique to them?
Thrombocytopenia
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
CD56
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

43. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Anti alpha subunit 3 of collagen on type IV bm
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

44. Which cytokines do Th2 release and For what?
Cyclosporine - OKT3
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

45. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
Activates Th1 helper cells; Macrophages
Cross link
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
Antihistone

46. What is oprelevkin? and What is it used for?
Activate macrophages
MS
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Recom IL 11; thrombocytopenia

47. What is thrombopoietin used for?
Thrombocytopenia
Activates cytotoxic CD 8 T cells as second signal
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Immunoflourescent staining of tissue biopsies

48. What are the symptoms of serum sickness?
A chemotactic factor for neutrophils
TLR ad nuclear receptors
IL 1 and IL 6
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

49. What does IL 2 do?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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
Anemias (esp due to renal failure)
Activates cytotoxic CD 8 T cells as second signal

50. How does complement link innate and adaptive?
Anti IF
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
SP infections
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

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USMLE Step 1 Immunology

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