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. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Anti viral and anti tumor
heavy chains
Its main effect is a defect in Ab opsonization for killing
Kill them because they have CD16 on them that recognize the FcG portion

2. Describe the capsular structure of a lymph node; What are the functions of the LN?
IgM and IgA
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
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
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

3. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
A chemotactic factor for neutrophils
Steroid responsive nephrotic syndrome
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Antidesmoglein

4. What is the main function of interferons?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Antidesmoglein
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
2 heavy chains and two light chains

5. What is the presentation of hyperIgM syndrome?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
active complement pathway
C5a
Severe pyogenic infections early in life

6. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
MHC class molecules bind to KIRS or CD94 to prevent killing
Superficial inguinal

7. What is the presentation of Brutons agammaglobulinemia?
cannot cross placenta
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
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
TNF alpha and IL1

8. What type of side chains are found on Fc region of an antibody?
Carbohydrate
Superficial inguinal
TLR ad nuclear receptors
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

9. A lymph node is a ________ lymphoid organ.
secondary
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
type four
heavy chains

10. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
C5a
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
B - T - and NK cells

11. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
T
Rheumatic arthritis
Give a vaccine with a peptide comp from it that the cell mediated immunity otherwise cant get to! like h.influenzae vaccine. then class switching and memory response can occur
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

12. other than mediating shock - what else does TNF alpha do? who releases it mainly?
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
Secretory component
Activates Th1 helper cells; Macrophages
Anti Jo -1

13. Name 5 ways Antibody diversity is generated?
MS - hay fever - SLE - goodpastures
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
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
delayed!

14. Which antibodies can be multimeric?
except hyperacute
IgM and IgA
Antidesmoglein
mesenchymal

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?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
IL 5
Macrophages - Dendritic cells - B cells
Previous transfusion; pregnant woman whose fetus had paternal antigens

16. What are four results of a splenectomy?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

17. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
T cell precursor
IgM and IgG
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Maculopapular rash (palm - soles - back - neck) - jaundice with bile duct necrosis - hepatosplenomegaly - diarrhea; bone marrow and liver transplants (rich with lymphocytes); SCID patient receiving whole blood transfusion

18. What are the autoantibodies for goodpastures syndrome?
Found in the red pulp; contains the cords of billroth or the splenic parenchyma that have APCs/Macrophages that closely interact with the basement membrane of the vasculature and where RBCs squeeze through into the parenchyma and interact with Macrop
Axillary
Anti alpha subunit 3 of collagen on type IV bm
MHC I - CD16 - CD56

19. What lymph node drains the breast?
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
Axillary
type four
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

20. What is the common variable immunodeficiency ? How is it different from Brutons?
Anti Ach receptor
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
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

21. is IgM an opsonizer?
Negative!
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Hemochromatosis

22. What lymph node drains the upper limb?
Not thymus - BM
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
Anti TSh receptor
Axillary

23. What cytokines to Th2 secrete?
MS - hay fever - SLE - goodpastures
IL 4 - 5 - 10 - 6
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
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

24. How do you test for chronic granulomatous disease?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
The igA found in breast milk
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Negative nitroblue tetrazolium reduction test

25. What is the presentation of common variable immunodef? and What are the labs?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
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
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
IgM and IgA

26. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
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
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)

27. What is the main function of TNF alpha? How does it do this?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
...
Antimicrosomal and antithyroglobulin
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

28. Which disease is associated withB B27?
Superficial inguinal
The patient could become cyanotic in the OR!
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Inferior mesenteric

29. where are complements produced?
Chronic granulomatous disease
Basophils! THey want IG E class switch!
Liver! (they are proteins circulating in the blood)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

30. Describe the Mannose Lectin pathway
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
IgAs in mothers breast milk!
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
Axillary

31. What are the mediators that mast cells release?
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
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
IgG
A chemotactic factor for neutrophils

32. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
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
Wiskott Aldrich syndrome
Complement activation (active in both)
Anti smooth muscle

33. Which is the main antibody that provides passive immunity to infants?
Celiac
pentamer
IgG
Kill them because they have CD16 on them that recognize the FcG portion

34. What is the late phase reaction of anaphylaxis allergy? what mediates it?
Anti TSh receptor
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)
Receiving preformed Antibodies
Type IV

35. Which MHC presents intracellular peptides? how so?
Sinusitis - otitis media - pneumonia
MHC I; from RER with help of the B2 microglobulin
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
Anti TSh receptor

36. which antibody is involved in the primary response or immediate response to an antigen?
IgM
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

37. How does complement link innate and adaptive?
Maculopapular rash (palm - soles - back - neck) - jaundice with bile duct necrosis - hepatosplenomegaly - diarrhea; bone marrow and liver transplants (rich with lymphocytes); SCID patient receiving whole blood transfusion
IgM and IgD
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

38. What lymph node drains the stomach?
Tetanus - Botulinum - HBV - Rabies
Macrophages - Dendritic cells - B cells
IgM
Celiac

39. What are the symptoms of serum sickness?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
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
Viral neutralization of igM and IgG!
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

40. What are some sinopulmonary infections?
When you select for which MHC it will have; take out the lymphs that self react
False! B cell class switching requires a second signal
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Sinusitis - otitis media - pneumonia

41. Leukocyte adhesion defect presents with...
Basophils! THey want IG E class switch!
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
neutrophilia!
IL 4

42. How is i Th1 helper cell inhibited?
Cytokine IL 10 secreted by Th2
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

43. Which diseases are associated with DR4?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Type IV
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
DM type I and RA

44. what characterizes an arthus reaction?
Negative!
Edema and necrosis in that region
Hereditary angioedema; PNH
Paracortex; viral infection

45. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Anti Jo -1
Histamine; post capillary venules - vasodilation
Antibody mediated cytotoxicity; either complement dependent or complement independent
IgA

46. What are the autoantibodies for Celiac disease?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE

47. Which disease is associated with DR7?
Macrophages - Dendritic cells - B cells
Steroid responsive nephrotic syndrome
Influenza; antigenic shift; antigenic drift
IgG

48. What is the pathogenesis of a candida skin test?
S. aureus - E. Coli - aspergillus
IgG
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
Delayed type hypersensitivity

49. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
Anti IF
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Immunosuppression after kidney transplantation
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

50. What is filgrastim and sargramostim? and What is it used for?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Activate macrophages
A chemotactic factor for neutrophils