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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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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 are some sinopulmonary infections?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Sinusitis - otitis media - pneumonia
Rheumatic arthritis
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

2. What is wiskott aldrich syndrome? What is its mode of inheritance? What is the pathogenesis of disease? What is its triad of presentation? what labs does it present with?
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Barrel hoop basement membrane fenestrations
Negative selection
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

3. Describe the capsular structure of a lymph node; What are the functions of the LN?
IgG
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
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
Activate macrophages

4. A lymph node is a ________ lymphoid organ.
Liver! (they are proteins circulating in the blood)
secondary
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
TNF alpha and IL1

5. What do multimeric antibodies require for assembly?
Not thymus - BM
Activates cytotoxic CD 8 T cells as second signal
A j chain
Celiac

6. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Local infection/inflammation; infection of the ln itself; metastasis
Previous transfusion; pregnant woman whose fetus had paternal antigens
Anti U1 RNP (ribonucleoprotein)

7. IgM can exist as a _______ also
IgE; by activating eosinophils
Fab portion
pentamer
IgG

8. Which MHC presents intracellular peptides? how so?
Negative nitroblue tetrazolium reduction test
MHC I; from RER with help of the B2 microglobulin
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Graves

9. Give an example of someone who could get hyperacute transplant rejection.
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Previous transfusion; pregnant woman whose fetus had paternal antigens
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
MHC I; from RER with help of the B2 microglobulin

10. What is the clinical use for sirolimus? what should you combine it with?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Activates cytotoxic CD 8 T cells as second signal
Axillary
Macrophages - Dendritic cells - B cells

11. What are the main cell surface proteins on B cells?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
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
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
False! B cell class switching requires a second signal

12. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
In the germinal center of secondary follicles (In the paler center)
Influenza; antigenic shift; antigenic drift
Cross link

13. What are the two signals required for Th1 cells? what happens after then activated?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Chronic granulomatous disease
acute phase reactants
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

14. What does IL 4 do?
Acts as second signal on B cells to induce class switching to IgE and IgG
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
not Ab mediated
Popliteal

15. What lymph node drains the scrotum?
Antidesmoglein
Barrel hoop basement membrane fenestrations
Superficial inguinal
IgM

16. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Anti alpha subunit 3 of collagen on type IV bm
Glycoproteins; HLA
type four
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

17. what cell surface marker is used for NK cells as it is unique to them?
NK cells
CD56
All MHC 1/CD8
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

18. Describe the interstitial tissue of a spleen including the sinuses. What type of cells are found in the four structures (cortex - paracortex - medulla and sinuses)?
T
IL 15; IL 12 - interferon Beta and interferon alpha
Negative!
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

19. which cytokine inhibits TH2 cells? secreted by who?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Interferon gamma; Th1
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
B - T - and NK cells

20. describe the pathogenesis of delayed type IV hypersensitivity
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Edema and necrosis in that region

21. when can graft versus host disease? What is the result?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
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
Superficial inguinal
IL 15; IL 12 - interferon Beta and interferon alpha

22. What are the two signals required for B cell class switching? Which is the second signal?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Secretory component
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Chronic granulomatous disease

23. 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
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Anti mitochondrial
MHC I - CD16 - CD56

24. What are the autoantibodies for Mixed connective tissue disease?
Secretory component
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Anti U1 RNP (ribonucleoprotein)
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

25. What are the autoantibodies for systemic sclerosis?
Anti topoisomerase
Anti Jo -1
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

26. What are the function of B cells?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Basophils! THey want IG E class switch!
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Anti Jo -1

27. What are the mediators that mast cells release?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
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
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

28. what prevents NK cells from killing normal cells if their default is to kill?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
MHC class molecules bind to KIRS or CD94 to prevent killing
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

29. where do somatic hypermutation and class switching occur?
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
Inferior mesenteric
In the germinal center of secondary follicles (In the paler center)
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

30. From where do cytokines come from?
The igA found in breast milk
Lymphocytes
Its a serine protease that activates apoptosis; NK and CD8
A chemotactic factor for neutrophils

31. What are the autoantibodies for other vasculitides?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
IgM and IgA

32. What are the autoantibodies for polymyositis and dermatomyositis?
secondary
active complement pathway
Anti Jo -1
IgAs in mothers breast milk!

33. What is the autoantibody for SLE that is nonspecific? Specific?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Graves
Hereditary angioedema; PNH
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

34. T/F B cells do not require a second signal
False! B cell class switching requires a second signal
Edema and necrosis in that region
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
The patient could become cyanotic in the OR!

35. Which disease is associated with DR7?
Inferior mesenteric
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Steroid responsive nephrotic syndrome
Anti Ach receptor

36. Only the _______ contribute to the Fc region
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Popliteal
heavy chains
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class

37. How is sirolimus different from tacrolimus?
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
CD56
T cell precursor
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)

38. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
IL 5
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Cytokine IL 10 secreted by Th2
Activates Th1 helper cells; Macrophages

39. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Cytokine IL 10 secreted by Th2
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
IL 15; IL 12 - interferon Beta and interferon alpha

40. where do NK cells develop?
Cross link
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
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

41. What is filgrastim and sargramostim? and What is it used for?
A - B - C; all the D's
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
active complement pathway
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

42. describe the classic complement pathway.
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Alternative splicing of mRNA
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
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

43. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Th cells fail to produce interferon gamma; a lot of IgE
acute phase reactants
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
active complement pathway

44. For which toxins are preformed antibodies (passive) given?
Tetanus - Botulinum - HBV - Rabies
MHC I - CD16 - CD56
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
Sinusitis - otitis media - pneumonia

45. What does Interferon alpha and beta do? how?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
pathogenesis
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

46. Other than stimulating fever - what else does IL 6 do?
Stimulate the liver to release acute phase reactants
TNF alpha and IL1
Local infection/inflammation; infection of the ln itself; metastasis
Cross link

47. What is the main cytokine that activates eosinophils?
Anti TSh receptor
IL 5
Yes
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

48. Which disease is associated with HLA A3?
heavy chains
carboxy terminal
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
Hemochromatosis

49. What are the autoantibodies for Celiac disease?
NK cells
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
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
heavy chains

50. What are the labs in brutons agammaglobulinemia?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
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
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation