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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. How do you test for type III hypersensitivity?
Popliteal
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
A - B - C; all the D's
Immunoflourescent staining of tissue biopsies

2. which of the transplant rejections is antibody mediated? why does it occur?
lowest concentration
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
isotype
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

3. What lymph node drains the scrotum?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
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
Superficial inguinal
Fc

4. in which immunodef order do you see a lot of pus? no pus?
Previous transfusion; pregnant woman whose fetus had paternal antigens
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Type IV
lowest concentration

5. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
Graves
IgAs in mothers breast milk!
IL 4
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

6. Which is the main antibody in the delayed or secondary response to an antigen?
...
Cytokine IL 10 secreted by Th2
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
IgG

7. What are the cell surface proteins on NK cells?
MHC I - CD16 - CD56
Glycoproteins; HLA
Complement activation (active in both)
Remove encapsulated bacateria

8. To what portion of the Antibody do the complements bind?
Fab portion
Anti IF
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Fc

9. Name the three opsonins
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
CRP - C3b - IgM
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Negative!

10. other than C3a - what other complement acts as an anaphyloxin?
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
TGF beta and IL 10
C5a
acute phase reactants

11. What are the cell surface proteins for Macrophages? which two are for opsonins?
dimer
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
IgG
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

12. What are the autoantibodies for goodpastures syndrome?
MHC I; from RER with help of the B2 microglobulin
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Anti alpha subunit 3 of collagen on type IV bm
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

13. What bugs can actually infect the lymph node itself?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Negative nitroblue tetrazolium reduction test
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
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

14. What is recomb beta interferon used for?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
MS
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Activates cytotoxic CD 8 T cells as second signal

15. Which MHC presents intracellular peptides? how so?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
C5a
MHC I; from RER with help of the B2 microglobulin

16. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

17. which cytokine inhibits TH2 cells? secreted by who?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
MS - hay fever - SLE - goodpastures
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Interferon gamma; Th1

18. What is the defect in hyper IgM syndrome? What are the lab results?
Paracortex; viral infection
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Interferon gamma and IL 2

19. What are the autoantibodies for sjorgens syndrome?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Anti SS- A (anti RO) and Anti SS- B

20. What kinds of receptors activate innate immunity?
Anti IF
2 heavy chains and two light chains
TLR ad nuclear receptors
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

21. which immunodeficiency presents with delayed separation of the umbilicus? ataxia? telangiectasia?albinism? anaphylaxis on exposure to blood products with IgA? tetany?retained primary teeth? 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
Cytokine IL 10 secreted by Th2
B - T - and NK cells
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

22. What happens in a secondary follicle?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Anti U1 RNP (ribonucleoprotein)
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
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE

23. What are the two signals required for B cell class switching? Which is the second signal?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
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

24. What is the common variable immunodeficiency ? How is it different from Brutons?
Anti alpha subunit 3 of collagen on type IV bm
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Sinusitis - otitis media - pneumonia

25. where are complements produced?
Liver! (they are proteins circulating in the blood)
pale central germinal centers
encapsulated
Anti mitochondrial

26. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
Axillary
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

27. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
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
...
Increases expression of MHC I and MHC II and also activates NK cells
lowest concentration

28. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
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
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
MS

29. Which disease is associated with DR7?
IgG
Steroid responsive nephrotic syndrome
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
carboxy terminal

30. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
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
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Th cells fail to produce interferon gamma; a lot of IgE
Daclizumab; prevent ACUTE rejection of renal transplant

31. The MALT/GALT are not...
encapsulated
RNA segment reassortment
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

32. Which type of selection of thymic development provides central tolerance?
Negative selection
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Sinusitis - otitis media - pneumonia
Recom IL 11; thrombocytopenia

33. Which antibody mediates immunity to worms? how?
Inferior mesenteric
Th2; Th1
IgE; by activating eosinophils
isotype

34. What is digoxin immune Fab used for?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Antidote for digoxin intoxication
Paracortex
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

35. What type of side chains are found on Fc region of an antibody?
Carbohydrate
IgAs in mothers breast milk!
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

36. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Cross link
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
TGF beta and IL 10
Rheumatic arthritis

37. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
acute phase reactants
Its main effect is a defect in Ab opsonization for killing
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

38. What happens in a deficiency of C3?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
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
delayed!
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

39. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Rheumatic arthritis
Superficial inguinal
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
T cell dysfunction

40. What are the two signals required for T cells? what happens after?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
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
MHC I - CD16 - CD56

41. What is the pathology seen in chronic transplant rejection?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
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

42. describe the pathogenesis of delayed type IV hypersensitivity
IL 3; supports growth and differentiation of bone marrow stem cells
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
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)

43. What is the pathology in hyperacute transplant rejection?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
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
When you select for which MHC it will have; take out the lymphs that self react
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

44. What is the clinical use of Muromonab?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
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)
Immunosuppression after kidney transplantation

45. Which antibodies can be multimeric?
Viral neutralization of igM and IgG!
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Fc
IgM and IgA

46. What do mature naive B lymphocytes express?
Anti topoisomerase
SP infections
Glycoproteins; HLA
IgM and IgD

47. What does IL 10 do? who is secreted by?
Paracortex; viral infection
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
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!
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

48. What are C1 - C2 - C3 - C4 important for?
Antihistone
Viral neutralization of igM and IgG!
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
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

49. What is the main function of TNF alpha? How does it do this?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Anti topoisomerase
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

50. What lymph node drains the anal canal (below the pectinate line)?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
encapsulated
The igA found in breast milk
Superficial inguinal