Test your basic knowledge |

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 lymph node drains the upper limb?
Anti IF
Receiving preformed Antibodies
Axillary
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

2. What are C1 - C2 - C3 - C4 important for?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Viral neutralization of igM and IgG!
MHC II - B7
DM type I and RA

3. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Th cells fail to produce interferon gamma; a lot of IgE
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
If there is class switching and plasma cell production (that is when memory cells are produced)

4. What is recomb beta interferon used for?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
MS - hay fever - SLE - goodpastures
MS

5. what will NK cells do to cells covered in IgG Ab? why?
Kill them because they have CD16 on them that recognize the FcG portion
Influenza; antigenic shift; antigenic drift
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
IL 4 - 5 - 10 - 6

6. What are the main cell surface proteins on B cells?
opsonizes
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Bind FcG for antibody dependent cellular cytotoxicity

7. What is hereditary angioedema? What are the C3 levels?
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
Paracortex
Pernicious Anemia and Hashimotos
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

8. What does IgA pick up from epithelial cells before being secreted?
...
Secretory component
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

9. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
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
Daclizumab; prevent ACUTE rejection of renal transplant
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
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

10. Which disease is associated with DR7?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Lymphocytes
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Steroid responsive nephrotic syndrome

11. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
Its a serine protease that activates apoptosis; NK and CD8
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 smooth muscle
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

12. What are target cells?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Cells that stil have weird parts of their membrane that macrophages usually bite off
Tetanus - Botulinum - HBV - Rabies
Glycoproteins; HLA

13. What are the three types of lymphocytes?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
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
B - T - and NK cells
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

14. what characterizes an arthus reaction?
IgM and IgA
Immunoflourescent staining of tissue biopsies
Edema and necrosis in that region
Anti Ach receptor

15. What are the autoantibodies for goodpastures syndrome?
Anti alpha subunit 3 of collagen on type IV bm
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
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

16. what happens in a deficiency of C1 esterase inhibitor? DAF?
Hereditary angioedema; PNH
MS - hay fever - SLE - goodpastures
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

17. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
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!
IgA
A j chain
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

18. How do you test for chronic granulomatous disease?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Basophils! THey want IG E class switch!
Negative nitroblue tetrazolium reduction test

19. What is the receptor for EBV? On what cells is that located?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Complement activation (active in both)
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

20. What does granulysin do?
Remove encapsulated bacateria
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
cannot cross placenta

21. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
If there is class switching and plasma cell production (that is when memory cells are produced)
except hyperacute
pathogenesis
Not thymus - BM

22. What is the pathogenesis of chronic transplant rejection? When does it occur? is it reversible?
Antidote for digoxin intoxication
secondary
MHC class molecules bind to KIRS or CD94 to prevent killing
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 :(

23. What part of the lymph node specifically expands during a cellular immune response? when would this occur?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
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
Antimicrosomal and antithyroglobulin
Paracortex; viral infection

24. What is the pathogenesis of a hypersensitivity reaction?
Carbohydrate
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
Antidote for digoxin intoxication
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

25. are Th cells involved in trapping of antigens of endotoxin/LPS?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
No because no peptide fragment!
neutrophilia!
IL 5

26. What is Aldesleukin? What is it used for
Stimulate the liver to release acute phase reactants
A recomb cytokine of IL 2; RCC and metastatic melanoma
Delayed type hypersensitivity
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

27. Which is the most abundant antibody in blood?
IgM and IgA
except hyperacute
IgG
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

28. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
NK cells
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
A j chain
Anti viral and anti tumor

29. which of the transplant rejections is antibody mediated? why does it occur?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
pathogenesis
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

30. What are the autoantibodies for type I diabetes mellitus?
Immunosuppression after kidney transplantation
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
Anti glutamate carboxylase and anti insulin
...

31. ________ regulate the cell mediated response.
Yes
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
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
Humoral

32. Which disease is associated with HLA A3?
Anti SS- A (anti RO) and Anti SS- B
CRP - C3b - IgM
Hemochromatosis
encapsulated

33. What is the autoantibody for SLE that is nonspecific? Specific?
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
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

34. The secondary follicles have __________; primary follicles are dense
except hyperacute
Anti viral and anti tumor
pale central germinal centers
Activate macrophages

35. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
TNF alpha and IL1
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

36. T/F B cells do not require a second signal
False! B cell class switching requires a second signal
IgG
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Anti TSh receptor

37. Describe the complement independent Type II hypersenstivity reaction. Give an example.
Negative!
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Anti viral and anti tumor

38. What lymph node drains the stomach?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Anti Jo -1
Celiac

39. What lymph node drains the anal canal (below the pectinate line)?
Thrombocytopenia
In IgE AIHA- it results in MAC attack (remember IgE is not an opsonin!) - in IgG AIHA C3b (and IgG) opsonization results in phagocytosis by fixed macrophages in the spleen
Complement activation (active in both)
Superficial inguinal

40. hat is the presentation of Jobs syndrome or Hyper IgE?
Immunoflourescent staining of tissue biopsies
Th cells fail to produce interferon gamma; a lot of IgE
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

41. other than C3a - what other complement acts as an anaphyloxin?
When you select for which MHC it will have; take out the lymphs that self react
T cell precursor
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
C5a

42. How is sirolimus different from tacrolimus?
Activates Th1 helper cells; Macrophages
Lymphocytes
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Paracortex; viral infection

43. 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)
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
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
Fab portion

44. What is filgrastim and sargramostim? and What is it used for?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Acts as second signal on B cells to induce class switching to IgE and IgG
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
...

45. which of the IL2 inhibitors produce nephrotoxicity? thrombocytopenia/leukopenia?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Anti Ach receptor
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
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

46. Describe complement dependent Type II hypersensitivity. Give an example.
TGF beta and IL 10
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
IgE
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

47. What lymph node drains the rectum (above the pectinate line)?
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
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Internal iliac
delayed!

48. In general What are T cells good for?
Cells that stil have weird parts of their membrane that macrophages usually bite off
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
dimer
Anti viral and anti tumor

49. Which diseases are associated with DR4?
B - T - and NK cells
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
DM type I and RA
except hyperacute

50. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
IL 4 - 5 - 10 - 6
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
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