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 is the main function of TNF alpha? How does it do this?
Anti mitochondrial
Chronic granulomatous disease
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

2. 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
Antimicrosomal and antithyroglobulin
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
IgE; by activating eosinophils

3. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
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
IL 15; IL 12 - interferon Beta and interferon alpha
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

4. What lymph node drains the rectum (above the pectinate line)?
Interferon gamma and IL 2
Internal iliac
Viral neutralization of igM and IgG!
Influenza; antigenic shift; antigenic drift

5. What are the autoantibodies for type I diabetes mellitus?
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
MS
Anti glutamate carboxylase and anti insulin
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

6. What is muromonab - CD3 (OKT3)
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Macrophages - Dendritic cells - B cells
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
IgA

7. other than C3a - what other complement acts as an anaphyloxin?
Anti glutamate carboxylase and anti insulin
C5a
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
No because no peptide fragment!

8. What does granulysin do?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
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
Anti topoisomerase
Superficial inguinal

9. What is the presentation of hyperIgM syndrome?
Severe pyogenic infections early in life
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Anti alpha subunit 3 of collagen on type IV bm
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

10. where do NK cells develop?
Immunoflourescent staining of tissue biopsies
Not thymus - BM
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

11. The ______ in the BM are DN - the DP are in the cortex of thymus
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
A j chain
T cell precursor
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

12. Which cytokines do Th2 release and For what?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Viral neutralization of igM and IgG!
A - B - C; all the D's

13. What are the main symptoms of T cell immunodeficiencies?
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
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
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
Intracellular pathogens (acute and chronic viruses and virally induced cancers)

14. Which is the main antibody that provides passive immunity to infants?
Influenza; antigenic shift; antigenic drift
Fab portion
Axillary
IgG

15. which antibodies can bind complement?
IgM and IgG
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
pale central germinal centers

16. What is colostrum?
The igA found in breast milk
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
neutrophilia!
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

17. Which diseases are associated with DR5?
Anti Ach receptor
Pernicious Anemia and Hashimotos
Paracortex; viral infection
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

18. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
A chemotactic factor for neutrophils
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

19. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
MS
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

20. The Fc region is found on the...
carboxy terminal
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Axillary
Hemochromatosis

21. which of the IL2 inhibitors produce nephrotoxicity? thrombocytopenia/leukopenia?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Basophils! THey want IG E class switch!
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Viral neutralization of igM and IgG!

22. What are the autoantibodies for primary biliary cirrhosis?
Anti mitochondrial
IgG
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
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

23. What are the autoantibodies for hashimotos?
Antimicrosomal and antithyroglobulin
Liver! (they are proteins circulating in the blood)
Acts as second signal on B cells to induce class switching to IgE and IgG
Immunosuppression after kidney transplantation

24. which interleukin receptor is required for NK development? activation?
Antidote for digoxin intoxication
NK cells
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
IL 15; IL 12 - interferon Beta and interferon alpha

25. What is the pathogenesis of a candida skin test?
Delayed type hypersensitivity
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
All MHC 1/CD8
Not thymus - BM

26. What are the three types of APCs?
Interferon gamma; Th1
Celiac
IL 1 and IL 6
Macrophages - Dendritic cells - B cells

27. What is the main function of IL 8?
A chemotactic factor for neutrophils
Fc
mesenchymal
Glycoproteins; HLA

28. are Th cells involved in trapping of antigens of endotoxin/LPS?
IgM and IgG
No because no peptide fragment!
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

29. Type Iv hypersensitivity is...
Superficial inguinal
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
delayed!
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

30. What is the general structure of an Ab?
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
2 heavy chains and two light chains
T cell activation; no with CD 4 or CD 8
Receiving preformed Antibodies

31. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
All MHC 1/CD8
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Delayed type hypersensitivity
Anemias (esp due to renal failure)

32. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
opsonizes
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
A chemotactic factor for neutrophils

33. Describe the interstitial tissue of a spleen including the sinuses. What type of cells are found in the four structures (cortex - paracortex - medulla and sinuses)?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
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
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after

34. What is the pathology in hyperacute transplant rejection?
mesenchymal
Activate macrophages
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Cyclosporine - OKT3

35. What are the autoantibodies for goodpastures syndrome?
Anti Ach receptor
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Anti alpha subunit 3 of collagen on type IV bm
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

36. What do mature naive B lymphocytes express?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
IgM and IgD
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
Its main effect is a defect in Ab opsonization for killing

37. Type IV hypersensitivity is i...
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
TGF beta and IL 10
Anemias (esp due to renal failure)
not Ab mediated

38. which cells have more complete tolerance - B or T cells?
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)
Complement activation (active in both)
dimer
T

39. What does IL 2 do?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Activates cytotoxic CD 8 T cells as second signal
Activate macrophages
Negative selection

40. __________ are a part of the innate system.
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
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Interferon gamma; Th1
NK cells

41. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Its main effect is a defect in Ab opsonization for killing
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
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
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

42. What are the autoantibodies for wegeners granulomatosis?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
cannot cross placenta
Negative nitroblue tetrazolium reduction test
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

43. what will NK cells do to cells covered in IgG Ab? why?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Chronic granulomatous disease
Kill them because they have CD16 on them that recognize the FcG portion

44. What lymph node drains the stomach?
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
RNA segment reassortment
Celiac
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

45. How is the thymus organized? what happens in each section?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Negative!
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

46. 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?
Previous transfusion; pregnant woman whose fetus had paternal antigens
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
C5a
Cytokine IL 10 secreted by Th2

47. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
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
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
Negative!

48. What is the treatment of acute transplant rejection?
By transcytosis
mesenchymal
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Cyclosporine - OKT3

49. What is the monoclonal antibody to IL2 on activated T cells? What is it used for?
Daclizumab; prevent ACUTE rejection of renal transplant
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Anti alpha subunit 3 of collagen on type IV bm
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

50. The two heavy chains of an antibody contribute to the...
Fab portion
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
CD56
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic