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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. The two heavy chains of an antibody contribute to the...
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
S. aureus - E. Coli - aspergillus
The patient could become cyanotic in the OR!
Fab portion

2. What is the main cytokine that activates eosinophils?
Activates cytotoxic CD 8 T cells as second signal
IL 5
Kill them because they have CD16 on them that recognize the FcG portion
Yes

3. The idiotype; the Fc portion determines the...
isotype
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
Cytokine IL 10 secreted by Th2
dimer

4. which of the transplant rejections is antibody mediated? why does it occur?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Remove encapsulated bacateria
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

5. What lymph node drains the duodenum - jejunum?
Superior mesenteric
Kill them because they have CD16 on them that recognize the FcG portion
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

6. What type of side chains are found on Fc region of an antibody?
T
Carbohydrate
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Tetanus - Botulinum - HBV - Rabies

7. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
A j chain

8. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
Acts as second signal on B cells to induce class switching to IgE and IgG
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

9. What are the mediators that mast cells release?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Lymphocytes
Anti Jo -1
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

10. What links the adaptive and innate immunity?
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
Its a serine protease that activates apoptosis; NK and CD8
Complement activation (active in both)
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)

11. where are complements produced?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Anti IF
T cell precursor
Liver! (they are proteins circulating in the blood)

12. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
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

13. In general What are T cells good for?
Anti viral and anti tumor
IgAs in mothers breast milk!
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Negative selection

14. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Activates Th1 helper cells; Macrophages
type four
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Wiskott Aldrich syndrome

15. What are the autoantibodies for hashimotos?
Wiskott Aldrich syndrome
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Antimicrosomal and antithyroglobulin
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

16. To what portion of the Antibody do the complements bind?
Fc
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
Th cells fail to produce interferon gamma; a lot of IgE
Paracortex; viral infection

17. What is epo used for?
RNA segment reassortment
IL 5
Anemias (esp due to renal failure)
A j chain

18. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Cross link
mesenchymal
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Antidesmoglein

19. What are the two signals required for B cell class switching? Which is the second signal?
Interferon gamma and IL 2
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
IL 4
IgE; by activating eosinophils

20. Which antibody mediates immunity to worms? how?
B - T - and 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
IgE; by activating eosinophils
Anti IF

21. Which disease is associated with B8?
Graves
type four
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Anti viral and anti tumor

22. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Lymphocytes
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Antibody mediated cytotoxicity; either complement dependent or complement independent
Type IV

23. What is the main function of TNF alpha? How does it do this?
2 heavy chains and two light chains
Carbohydrate
Antibody mediated cytotoxicity; either complement dependent or complement independent
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

24. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Severe pyogenic infections early in life
Axillary
Its main effect is a defect in Ab opsonization for killing

25. What can cause a lymph node enlargement?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Hemochromatosis
Local infection/inflammation; infection of the ln itself; metastasis

26. IgE has the ___________ in the serum
lowest concentration
Pernicious Anemia and Hashimotos
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

27. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
IL 3; supports growth and differentiation of bone marrow stem cells
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
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
The igA found in breast milk

28. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Th2; Th1
dimer
Influenza; antigenic shift; antigenic drift
secondary

29. Which are the only two antiinflammatory cytokines?
TGF beta and IL 10
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Not thymus - BM
Antidote for digoxin intoxication

30. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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

31. The lymphocytes are ________ origin
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Negative!
mesenchymal
IL 4 - 5 - 10 - 6

32. What is the clinical use of Muromonab?
SP infections
Immunosuppression after kidney transplantation
Liver! (they are proteins circulating in the blood)
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

33. which cytokine inhibits TH2 cells? secreted by who?
Kill them because they have CD16 on them that recognize the FcG portion
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
IgE; by activating eosinophils
Interferon gamma; Th1

34. What is passive immunity?
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
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
Receiving preformed Antibodies
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

35. other than C3a - what other complement acts as an anaphyloxin?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Alternative splicing of mRNA
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
C5a

36. What does IL 4 do?
A chemotactic factor for neutrophils
Acts as second signal on B cells to induce class switching to IgE and IgG
neutrophilia!
A j chain

37. What is the pathogenesis of a candida skin test?
Delayed type hypersensitivity
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
neutrophilia!
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

38. What is the clinical use for azathioprine?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
...
Antidesmoglein

39. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
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
Cyclosporine - OKT3
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

40. The secondary follicles have __________; primary follicles are dense
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
pale central germinal centers
IgG

41. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Alternative splicing of mRNA
TNF alpha and IL1

42. What are the autoantibodies for systemic sclerosis?
TNF alpha and IL1
Anti topoisomerase
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
Activates Th1 helper cells; Macrophages

43. What is the receptor for EBV? On what cells is that located?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
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
Viral neutralization of igM and IgG!
CD21 on B cells (although there is T cell lymphocytosis in EBV)

44. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
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
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
TNF alpha and IL1

45. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
mesenchymal

46. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
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
IgM
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

47. what mediates the type II hypersensitivity? What are the two different methods?
Antibody mediated cytotoxicity; either complement dependent or complement independent
Carbohydrate
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Superficial inguinal

48. What are howell jolly bodies?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
T cell dysfunction
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

49. If an antigen lacks a peptide component How does the adaptive immunity attack it? What type of response is this called. give an example of bugs that do this. what implications does this have on splenectomy?
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Steroid responsive nephrotic syndrome
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
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

50. What lymph node drains the lateral side of the dorsum of the foot?
Activates Th1 helper cells; Macrophages
Popliteal
Carbohydrate
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)