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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 amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Histamine; post capillary venules - vasodilation
Graves
IL 1 and IL 6
Anti IF

2. where do somatic hypermutation and class switching occur?
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
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
In the germinal center of secondary follicles (In the paler center)
CD21 on B cells (although there is T cell lymphocytosis in EBV)

3. which of the hypersensitivity reactions is not Ab mediated?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Type IV
RNA segment reassortment
Chronic granulomatous disease

4. Other than stimulating fever - what else does IL 6 do?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Stimulate the liver to release acute phase reactants

5. Which is the main antibody that provides passive immunity to infants?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
IgG
False! B cell class switching requires a second signal
C5a

6. which B and T cell disorder presents with specifically low IgM?
Secretory component
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Wiskott Aldrich syndrome
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

7. What is the toxicity of azathioprine?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
...
False! B cell class switching requires a second signal
Th2; Th1

8. What is the common variable immunodeficiency ? How is it different from Brutons?
Influenza; antigenic shift; antigenic drift
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
TGF beta and IL 10
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

9. What are superantigens? give two examples.
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
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
active complement pathway
...

10. What is the late phase reaction of anaphylaxis allergy? what mediates it?
Anti viral and anti tumor
TLR ad nuclear receptors
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)
acute phase reactants

11. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
encapsulated
Severe pyogenic infections early in life
IL 3; supports growth and differentiation of bone marrow stem cells

12. What is oprelevkin? and What is it used for?
Superficial inguinal
Recom IL 11; thrombocytopenia
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
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

13. The lymphocytes are ________ origin
Steroid responsive nephrotic syndrome
Not thymus - BM
Negative!
mesenchymal

14. What is recomb beta interferon used for?
MS
Anemias (esp due to renal failure)
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
opsonizes

15. 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 alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Th cells fail to produce interferon gamma; a lot of IgE
Interferon gamma and IL 2

16. What is the pathogenesis of chronic transplant rejection? When does it occur? is it reversible?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
T cell and antibody mediated vascular damage due to MHC non self being recognized as self by self lymphocytes and resulting in attack of the foreign antigens it presents (all of them); months to years after; no :(
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

17. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
Superficial inguinal
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

18. Which antibodies can be multimeric?
Local infection/inflammation; infection of the ln itself; metastasis
Anti glutamate carboxylase and anti insulin
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
IgM and IgA

19. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
T cell precursor
Its main effect is a defect in Ab opsonization for killing
T
Immunosuppression after kidney transplantation

20. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Pernicious Anemia and Hashimotos
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
lowest concentration
DM type I

21. What is the pathology in hyperacute transplant rejection?
acute phase reactants
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
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
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

22. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
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
IL 4 - 5 - 10 - 6
Steroid responsive nephrotic syndrome
Th cells fail to produce interferon gamma; a lot of IgE

23. What are the autoantibodies for autoimmune hepatitis?
Edema and necrosis in that region
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
IgG
Anti smooth muscle

24. What is the most common example of passive immunity?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
IgAs in mothers breast milk!
Histamine; post capillary venules - vasodilation
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

25. To what portion of the Antibody do the complements bind?
Fc
...
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Active; passive - fast but short half life (3 weeks!)

26. What is the main cytokine released by T cells? What does it do
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
Anti Jo -1
IL 3; supports growth and differentiation of bone marrow stem cells
TLR ad nuclear receptors

27. How does complement link innate and adaptive?
DM type I
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Severe pyogenic infections early in life

28. What is a type I hypersensitivity reaction? What is atopic?
Basophils! THey want IG E class switch!
Anti TSh receptor
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
CD21 on B cells (although there is T cell lymphocytosis in EBV)

29. For which toxins are preformed antibodies (passive) given?
Anti alpha subunit 3 of collagen on type IV bm
Axillary
isotype
Tetanus - Botulinum - HBV - Rabies

30. What are the autoantibodies for systemic sclerosis?
Anti topoisomerase
Influenza; antigenic shift; antigenic drift
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Activate macrophages

31. which type of immunity is slow but long lasting? as opposed to...
Celiac
Active; passive - fast but short half life (3 weeks!)
Local infection/inflammation; infection of the ln itself; metastasis
carboxy terminal

32. Name two endogenous pyrogens
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
IL 1 and IL 6
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

33. what prevents NK cells from killing normal cells if their default is to kill?
MHC class molecules bind to KIRS or CD94 to prevent killing
Local infection/inflammation; infection of the ln itself; metastasis
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
Anti SS- A (anti RO) and Anti SS- B

34. How is i Th1 helper cell inhibited?
not Ab mediated
Graves
Cytokine IL 10 secreted by Th2
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

35. Which diseases are associated with DR2?
...
A - B - C; all the D's
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
MS - hay fever - SLE - goodpastures

36. What are the two signals required for T cells? what happens after?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
IL 4
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
C5a

37. what mediates the type II hypersensitivity? What are the two different methods?
IgG
RNA segment reassortment
Th cells fail to produce interferon gamma; a lot of IgE
Antibody mediated cytotoxicity; either complement dependent or complement independent

38. What lymph node drains the stomach?
Superficial inguinal
Carbohydrate
Celiac
MHC I - CD16 - CD56

39. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
TGF beta and IL 10
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

40. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
isotype
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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
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

41. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
Antidesmoglein
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
MS - hay fever - SLE - goodpastures
Cells that stil have weird parts of their membrane that macrophages usually bite off

42. What are the main symptoms of T cell immunodeficiencies?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Paracortex
IgM and IgD
Intracellular pathogens (acute and chronic viruses and virally induced cancers)

43. What is the main function of TNF alpha? How does it do this?
Fab portion
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Anti glutamate carboxylase and anti insulin

44. Which HLA's are included in MHC I? MHC II?

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45. What are four results of a splenectomy?
Th cells fail to produce interferon gamma; a lot of IgE
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Anti U1 RNP (ribonucleoprotein)
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

46. What lymph node drains the testes?
Celiac
Para aortic
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
The patient could become cyanotic in the OR!

47. What kinds of receptors activate innate immunity?
IL 3; supports growth and differentiation of bone marrow stem cells
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
TLR ad nuclear receptors
Edema and necrosis in that region

48. What cytokines to Th2 secrete?
IgG
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
IL 4 - 5 - 10 - 6
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

49. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
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
CD21 on B cells (although there is T cell lymphocytosis in EBV)

50. What is the toxicity of muromonab?
Anti TSh receptor
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
B - T - and NK cells
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated