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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. Type IV hypersensitivity is i...
not Ab mediated
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Superior mesenteric
Its main effect is a defect in Ab opsonization for killing

2. What is a type I hypersensitivity reaction? What is atopic?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Not thymus - BM
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
MHC II - B7

3. What is the main function of TNF alpha? How does it do this?
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
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
TLR ad nuclear receptors
Activates Th1 helper cells; Macrophages

4. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
secondary
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
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
heavy chains

5. What is the clinical use of Muromonab?
IL 3; supports growth and differentiation of bone marrow stem cells
Immunosuppression after kidney transplantation
S. aureus - E. Coli - aspergillus
Antidesmoglein

6. What are the cell surface proteins on NK cells?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Interferon gamma and IL 2
Its main effect is a defect in Ab opsonization for killing
MHC I - CD16 - CD56

7. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Superficial inguinal
Antihistone
Acts as second signal on B cells to induce class switching to IgE and IgG
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

8. What are the autoantibodies for systemic sclerosis?
Celiac
Active; passive - fast but short half life (3 weeks!)
By transcytosis
Anti topoisomerase

9. The lymphocytes are ________ origin
Popliteal
mesenchymal
Sinusitis - otitis media - pneumonia
IL 4

10. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
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
Thrombocytopenia
IgE

11. what characterizes an arthus reaction?
DM type I
Daclizumab; prevent ACUTE rejection of renal transplant
Edema and necrosis in that region
Its main effect is a defect in Ab opsonization for killing

12. What is epo used for?
Anemias (esp due to renal failure)
Glycoproteins; HLA
Increases expression of MHC I and MHC II and also activates NK cells
Graves

13. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
neutrophilia!
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Sinusitis - otitis media - pneumonia

14. are Th cells involved in trapping of antigens of endotoxin/LPS?
IgM and IgA
Recom IL 11; thrombocytopenia
No because no peptide fragment!
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

15. What is colostrum?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
In the germinal center of secondary follicles (In the paler center)
CRP - C3b - IgM
The igA found in breast milk

16. IgM can fix complement but...
Internal iliac
cannot cross placenta
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
...

17. So antibodies are the effectors for the humoral response. List some of their functions.
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Antidote for digoxin intoxication
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
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

18. How do you test for type III hypersensitivity?
Anti mitochondrial
Immunoflourescent staining of tissue biopsies
Soluble C3 spontaneously hydrolyzes spontaneously to C3b and opsonizes microbial and host cell surfaces and accumulates on surfaces; C3b activates C5 convertase which leads to MAC activation
Hereditary angioedema; PNH

19. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

20. What are the two signals to kill for NK cells?
IgG
No because no peptide fragment!
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Basophils! THey want IG E class switch!

21. What is filgrastim and sargramostim? and What is it used for?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
except hyperacute
dimer
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

22. What bugs can actually infect the lymph node itself?
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
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Superior mesenteric

23. Which diseases are associated with DR2?
Antidesmoglein
...
MS - hay fever - SLE - goodpastures
No because no peptide fragment!

24. What does interferon gamma do? What two type of cells does it attack mostly?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
IgA
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

25. what cell surface marker is used for NK cells as it is unique to them?
CD56
Cyclosporine - OKT3
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Basophils! THey want IG E class switch!

26. What does interferon gamma do to be antiviral?
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
Increases expression of MHC I and MHC II and also activates NK cells
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

27. What is the clinical use for sirolimus? what should you combine it with?
CRP - C3b - IgM
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

28. Only the _______ contribute to the Fc region
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
MHC class molecules bind to KIRS or CD94 to prevent killing
heavy chains
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)

29. 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?
MHC I; from RER with help of the B2 microglobulin
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
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
carboxy terminal

30. Name two endogenous pyrogens
IL 1 and IL 6
Type IV
...
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

31. What is the late phase reaction of anaphylaxis allergy? what mediates it?
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)
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
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
Type IV

32. What is recomb beta interferon used for?
Basophils! THey want IG E class switch!
MS
IgAs in mothers breast milk!
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

33. Which antibody mediates immunity to worms? how?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Viral neutralization of igM and IgG!
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
IgE; by activating eosinophils

34. which antibodies prevent antigens from binding mucosal surfaces?
IgA
Soluble C3 spontaneously hydrolyzes spontaneously to C3b and opsonizes microbial and host cell surfaces and accumulates on surfaces; C3b activates C5 convertase which leads to MAC activation
Inferior mesenteric
Negative nitroblue tetrazolium reduction test

35. What lymph node drains the sigmoid colon?
Inferior mesenteric
Anti U1 RNP (ribonucleoprotein)
Anti topoisomerase
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

36. Which is the most abundant antibody in blood?
Acts as second signal on B cells to induce class switching to IgE and IgG
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
IgG
A chemotactic factor for neutrophils

37. What is the presentation of hyperIgM syndrome?
C5a
Severe pyogenic infections early in life
Antihistone
Thrombocytopenia

38. What are howell jolly bodies?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
IgM and IgA
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

39. Monomer in circulation - ___ when secreted
Tetanus - Botulinum - HBV - Rabies
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
dimer
A recomb cytokine of IL 2; RCC and metastatic melanoma

40. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
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
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IgG
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

41. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Cytokine IL 10 secreted by Th2
...
Anti smooth muscle
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

42. which antibodies can bind complement?
IgM and IgG
IL 15; IL 12 - interferon Beta and interferon alpha
Axillary
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

43. What are the autoantibodies for type I diabetes mellitus?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
MHC class molecules bind to KIRS or CD94 to prevent killing
Anti glutamate carboxylase and anti insulin
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

44. What are the autoantibodies for primary biliary cirrhosis?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Anti mitochondrial
When you select for which MHC it will have; take out the lymphs that self react
Type IV

45. Which are the only two antiinflammatory cytokines?
IgM
TGF beta and IL 10
Hereditary angioedema; PNH
not Ab mediated

46. What is the presentation of Brutons agammaglobulinemia?
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
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
Complement activation (active in both)
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

47. What is the presentation of common variable immunodef? and What are the labs?
A - B - C; all the D's
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
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
C5a

48. What are the autoantibodies for drug induced lupus?
Acts as second signal on B cells to induce class switching to IgE and IgG
Antihistone
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Steroid responsive nephrotic syndrome

49. describe the pathogenesis of delayed type IV hypersensitivity
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
pale central germinal centers
SP infections
2 heavy chains and two light chains

50. What links the adaptive and innate immunity?
Sinusitis - otitis media - pneumonia
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Complement activation (active in both)