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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 does IL 2 do?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
IgE; by activating eosinophils
Kill them because they have CD16 on them that recognize the FcG portion
Activates cytotoxic CD 8 T cells as second signal

2. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
isotype
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

3. What is the receptor for EBV? On what cells is that located?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
The igA found in breast milk
CD21 on B cells (although there is T cell lymphocytosis in EBV)
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

4. What is Aldesleukin? What is it used for
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
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
A recomb cytokine of IL 2; RCC and metastatic melanoma
Basophils! THey want IG E class switch!

5. What lymph node drains the lateral side of the dorsum of the foot?
Popliteal
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

6. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
Liver! (they are proteins circulating in the blood)
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
Interferon gamma and IL 2
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

7. In general What are T cells good for?
Anti viral and anti tumor
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
All MHC 1/CD8
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

8. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
heavy chains
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

9. what results in symptoms of shock in an acute hemolytic transfusion reaction?
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
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
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
Viral neutralization of igM and IgG!

10. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
Rheumatic arthritis
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
MHC II - B7
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

11. Other than stimulating fever - what else does IL 6 do?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Stimulate the liver to release acute phase reactants
MHC I - CD16 - CD56
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

12. Type IV hypersensitivity is i...
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
Increases expression of MHC I and MHC II and also activates NK cells
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
not Ab mediated

13. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
IgG
encapsulated
except hyperacute
CD56

14. What are some catalase positive organisms?
T cell activation; no with CD 4 or CD 8
Anti Jo -1
S. aureus - E. Coli - aspergillus
Activates Th1 helper cells; Macrophages

15. What are the T cell functions?
Hemochromatosis
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Anti alpha subunit 3 of collagen on type IV bm
Antidote for digoxin intoxication

16. What is three common causes of severe combined immunodef? What is the result of all three?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Delayed type hypersensitivity
Popliteal
Cells that stil have weird parts of their membrane that macrophages usually bite off

17. What lymph node drains the testes?
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
CRP - C3b - IgM
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!
Para aortic

18. Which type of selection of thymic development provides central tolerance?
Internal iliac
active complement pathway
Barrel hoop basement membrane fenestrations
Negative selection

19. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Glycoproteins; HLA
All MHC 1/CD8

20. What are the autoantibodies for wegeners granulomatosis?
Axillary
Anemias (esp due to renal failure)
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

21. What are howell jolly bodies?
Viral neutralization of igM and IgG!
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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
Interferon gamma; Th1

22. What are some sinopulmonary infections?
Sinusitis - otitis media - pneumonia
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
In the germinal center of secondary follicles (In the paler center)

23. Which are the only two antiinflammatory cytokines?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
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
Anti viral and anti tumor

24. What is muromonab - CD3 (OKT3)
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Internal iliac
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
carboxy terminal

25. What does interferon gamma do to be antiviral?
Increases expression of MHC I and MHC II and also activates NK cells
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Viral neutralization of igM and IgG!
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

26. Which disease is associated with DR7?
isotype
Steroid responsive nephrotic syndrome
heavy chains
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

27. What portion of the lymph node is not well developed in DiGeorge Syndrome?
Basophils! THey want IG E class switch!
Bind FcG for antibody dependent cellular cytotoxicity
Paracortex
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

28. What is recomb beta interferon used for?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
neutrophilia!
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
MS

29. Describe the complement independent Type II hypersenstivity reaction. Give an example.
Axillary
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Th2; Th1
Alternative splicing of mRNA

30. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Acts as second signal on B cells to induce class switching to IgE and IgG
DM type I and RA
Glycoproteins; HLA

31. what prevents NK cells from killing normal cells if their default is to kill?
B - T - and NK cells
MHC class molecules bind to KIRS or CD94 to prevent killing
Delayed type hypersensitivity
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

32. What happens in a secondary follicle?
Kill them because they have CD16 on them that recognize the FcG portion
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Negative selection

33. Which diseases are associated with DR4?
TLR ad nuclear receptors
DM type I and RA
Anti glutamate carboxylase and anti insulin
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

34. Leukocyte adhesion defect presents with...
neutrophilia!
The igA found in breast milk
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
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

35. What are the cell surface proteins on NK cells?
CRP - C3b - IgM
encapsulated
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
MHC I - CD16 - CD56

36. What are the main cell surface proteins on B cells?
Thrombocytopenia
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
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Superficial inguinal

37. Which disease is associated withB B27?
Recom IL 11; thrombocytopenia
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
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
pale central germinal centers

38. What do multimeric antibodies require for assembly?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
IL 3; supports growth and differentiation of bone marrow stem cells
Celiac
A j chain

39. How do you test for chronic granulomatous disease?
IgG
Graves
Negative nitroblue tetrazolium reduction test
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

40. What do mature naive B lymphocytes express?
The patient could become cyanotic in the OR!
IL 1 and IL 6
IgM and IgD
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

41. What lymph node drains the sigmoid colon?
Inferior mesenteric
In the germinal center of secondary follicles (In the paler center)
If there is class switching and plasma cell production (that is when memory cells are produced)
Superficial inguinal

42. 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?
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
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
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
All MHC 1/CD8

43. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Interferon gamma and IL 2
Sinusitis - otitis media - pneumonia
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

44. __________ are a part of the innate system.
isotype
NK cells
TNF alpha and IL1
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

45. What lymph node drains the scrotum?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Superficial inguinal
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

46. hat is the presentation of Jobs syndrome or Hyper IgE?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
delayed!
Th2; Th1
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

47. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Its main effect is a defect in Ab opsonization for killing
not Ab mediated
No because no peptide fragment!

48. What is the clinical use for azathioprine?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
...
Stimulate the liver to release acute phase reactants

49. How is i Th1 helper cell inhibited?
active complement pathway
Paracortex; viral infection
Cytokine IL 10 secreted by Th2
Hereditary angioedema; PNH

50. In order to produce Antibodies - does the antigen have to be phagocytosed? give an example with a bug and an autoimmune (type II hypersensitivity for example).
Axillary
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!
Basophils! THey want IG E class switch!
Antimicrosomal and antithyroglobulin