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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
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 is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Increases expression of MHC I and MHC II and also activates NK cells

2. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
DM type I
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

3. Complements are...
acute phase reactants
CRP - C3b - IgM
MHC I - CD16 - CD56
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

4. What does interferon gamma do to be antiviral?
Increases expression of MHC I and MHC II and also activates NK cells
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
carboxy terminal
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

5. What is the main function of IL 12? other than macrophages who else can release IL 12?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
pathogenesis
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

6. Leukocyte adhesion defect presents with...
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
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
IgM and IgG
neutrophilia!

7. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Fc
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

8. What does granulysin do?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
TLR ad nuclear receptors
Activates cytotoxic CD 8 T cells as second signal
pathogenesis

9. What is serum sickness? give an example.
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
Hereditary angioedema; PNH
No because no peptide fragment!
Basophils! THey want IG E class switch!

10. What kinds of receptors activate innate immunity?
DM type I
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
TLR ad nuclear receptors
Th cells fail to produce interferon gamma; a lot of IgE

11. What is colostrum?
The igA found in breast milk
Cytokine IL 10 secreted by Th2
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IL 1 and IL 6

12. What does IL 10 do? who is secreted by?
Macrophages - Dendritic cells - B cells
Stimulate the liver to release acute phase reactants
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
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

13. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Glycoproteins; HLA
Histamine; post capillary venules - vasodilation
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

14. What is the presentation of scid? treatment?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
MHC I - CD16 - CD56
isotype
Hemochromatosis

15. which cytokine inhibits TH2 cells? secreted by who?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Interferon gamma; Th1
Anti topoisomerase
C5a

16. What are the autoantibodies for polymyositis and dermatomyositis?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Anti Jo -1
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
opsonizes

17. What are the three types of APCs?
Interferon gamma; Th1
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Macrophages - Dendritic cells - B cells

18. What is the receptor for EBV? On what cells is that located?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Tetanus - Botulinum - HBV - Rabies

19. What is the mode of inheritance of Chediak Higashi syndrome? What is the disease d/t? What does it result in? What is the presentation?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Th2; Th1
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

20. What lymph node drains the sigmoid colon?
Negative selection
Immunosuppression after kidney transplantation
Inferior mesenteric
Antidesmoglein

21. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
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
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

22. What does interferon gamma do? What two type of cells does it attack mostly?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

23. other than mediating shock - what else does TNF alpha do? who releases it mainly?
IgG
Activates Th1 helper cells; Macrophages
DM type I
Increases expression of MHC I and MHC II and also activates NK cells

24. What is filgrastim and sargramostim? and What is it used for?
Sinusitis - otitis media - pneumonia
pathogenesis
not Ab mediated
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

25. What happens in a secondary follicle?
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

26. What is the presentation of hyperIgM syndrome?
neutrophilia!
Superior mesenteric
Severe pyogenic infections early in life
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

27. which antibodies prevent antigens from binding mucosal surfaces?
IgA
IgG
opsonizes
Paracortex; viral infection

28. What are the sinusoids of the spleen? What is the difference between a spleen and a lymph node?
Anti topoisomerase
Immunosuppression after kidney transplantation
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
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

29. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
Anti viral and anti tumor
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
TNF alpha and IL1

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

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31. What are the two signals required for T cells? what happens after?
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Antihistone
Anti mitochondrial
Basophils! THey want IG E class switch!

32. The alternative pathway is the only constutively...
active complement pathway
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Daclizumab; prevent ACUTE rejection of renal transplant
CRP - C3b - IgM

33. What is recomb alpha interferon used for?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Anti SS- A (anti RO) and Anti SS- B
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
2 heavy chains and two light chains

34. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
T
Antidote for digoxin intoxication

35. Which is the main antibody in the delayed or secondary response to an antigen?
MS
IgG
Bind FcG for antibody dependent cellular cytotoxicity
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

36. What cytokines are released by Th1 cells?
Hereditary angioedema; PNH
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Interferon gamma and IL 2
Anti topoisomerase

37. IgE has the ___________ in the serum
TGF beta and IL 10
lowest concentration
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

38. What are the autoantibodies for wegeners granulomatosis?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
S. aureus - E. Coli - aspergillus
Kill them because they have CD16 on them that recognize the FcG portion
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

39. Which disease is associated with DR3?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
DM type I
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

40. What is digoxin immune Fab used for?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and 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
Antidote for digoxin intoxication
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

41. What are the two signals required for Th1 cells? what happens after then activated?
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
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
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Antidesmoglein

42. What are the two signals required for B cell class switching? Which is the second signal?
IL 15; IL 12 - interferon Beta and interferon alpha
The patient could become cyanotic in the OR!
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
opsonizes

43. Which diseases are associated with DR2?
MHC class molecules bind to KIRS or CD94 to prevent killing
MS - hay fever - SLE - goodpastures
Active; passive - fast but short half life (3 weeks!)
MS

44. From where do cytokines come from?
Lymphocytes
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
MS
Axillary

45. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Anti Jo -1
Fc
Cross link
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

46. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
Anti glutamate carboxylase and anti insulin
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
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
dimer

47. What are the autoantibodies for hashimotos?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Antimicrosomal and antithyroglobulin
Antihistone
Activates Th1 helper cells; Macrophages

48. are Th cells involved in trapping of antigens of endotoxin/LPS?
No because no peptide fragment!
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

49. What happens in a deficiency of C3?
Activates cytotoxic CD 8 T cells as second signal
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
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
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

50. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
Daclizumab; prevent ACUTE rejection of renal transplant
type four
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)