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 duodenum - jejunum?
Superior mesenteric
RNA segment reassortment
Increases expression of MHC I and MHC II and also activates NK cells
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

2. How is sirolimus different from tacrolimus?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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!
Edema and necrosis in that region
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

3. is IgM an opsonizer?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Negative!
IL 5
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

4. IgM can fix complement but...
cannot cross placenta
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Anti smooth muscle
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

5. So antibodies are the effectors for the humoral response. List some of their functions.
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Complement activation (active in both)
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!

6. which antibodies can bind complement?
IgM and IgG
Axillary
Not thymus - BM
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

7. give an example of how influenza does a major antigenic shift.
mesenchymal
Basophils! THey want IG E class switch!
pale central germinal centers
RNA segment reassortment

8. Other than stimulating fever - what else does IL 6 do?
IL 5
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Daclizumab; prevent ACUTE rejection of renal transplant
Stimulate the liver to release acute phase reactants

9. What are the autoantibodies for hashimotos?
Antimicrosomal and antithyroglobulin
Histamine; post capillary venules - vasodilation
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
Digeorge syndrome - 22q11 deletion resulting in failure to develop 3rd and 4th pharyngeal pouches; cardiac and great vessel congenital defects - tetany from hypocalcemia - recurrent viral/fungal infections from T cell deficiency; hypoPTH - hypoCa - a

10. How is the thymus organized? what happens in each section?
The igA found in breast milk
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
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
Paracortex

11. What are the major functions of Antibodies?
Viral neutralization of igM and IgG!
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Negative nitroblue tetrazolium reduction test

12. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
All MHC 1/CD8

13. What is epo used for?
Anemias (esp due to renal failure)
secondary
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

14. What is the presentation of hyperIgM syndrome?
Severe pyogenic infections early in life
SP infections
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

15. In general What are T cells good for?
Tetanus - Botulinum - HBV - Rabies
Anti viral and anti tumor
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

16. What are the autoantibodies for Celiac disease?
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Paracortex
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Anti TSh receptor

17. __________ are a part of the innate system.
TLR ad nuclear receptors
NK cells
Histamine; post capillary venules - vasodilation
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

18. what cell surface proteins are on all APCs?
IgE; by activating eosinophils
IgG
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
MHC II - B7

19. What are the T cell functions?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Increases expression of MHC I and MHC II and also activates NK cells
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

20. What are the main symptoms of T cell immunodeficiencies?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
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
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
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

21. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
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
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Yes
Daclizumab; prevent ACUTE rejection of renal transplant

22. What are the autoantibodies for autoimmune hepatitis?
active complement pathway
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Anti smooth muscle

23. Type Iv hypersensitivity is...
not Ab mediated
delayed!
mesenchymal
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

24. What does granulysin do?
pentamer
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
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
not Ab mediated

25. What does IL 5 do?
Hereditary angioedema; PNH
Acts as second signal on B cells to induce class switching to IgE and IgG
Local infection/inflammation; infection of the ln itself; metastasis
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils

26. What type of fenestrations are found in the red pulp of the spleen?
Barrel hoop basement membrane fenestrations
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
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

27. What are the main Cell surface proteins on T cells?
Th2; Th1
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!
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Histamine; post capillary venules - vasodilation

28. What are four results of a splenectomy?
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
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Not thymus - BM
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

29. What does Interferon alpha and beta do? how?
delayed!
Type IV
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
mesenchymal

30. What is the presentation of scid? treatment?
Pernicious Anemia and Hashimotos
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Histamine; post capillary venules - vasodilation

31. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
Anti U1 RNP (ribonucleoprotein)
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

32. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

33. What is recomb beta interferon used for?
Sinusitis - otitis media - pneumonia
MS
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Local infection/inflammation; infection of the ln itself; metastasis

34. What are the autoantibodies for graves?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Anti TSh receptor
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

35. Name the three opsonins
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
CRP - C3b - IgM
Anti mitochondrial
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

36. How does complement link innate and adaptive?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
encapsulated
acute phase reactants

37. 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
...
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
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

38. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
Complement activation (active in both)
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
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
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

39. What are the autoantibodies for polymyositis and dermatomyositis?
No because no peptide fragment!
Anti Jo -1
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

40. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Viral neutralization of igM and IgG!
Steroid responsive nephrotic syndrome
Anti alpha subunit 3 of collagen on type IV bm

41. 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
Antibody mediated cytotoxicity; either complement dependent or complement independent
Edema and necrosis in that region
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

42. What is the difference of IgE AIHA and IgG AIHA if they are both complement dependent type II hypersensitivities?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Negative selection
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

43. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
NK cells
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Antibody mediated cytotoxicity; either complement dependent or complement independent
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

44. What is the main function of IL 8?
Celiac
MHC I - CD16 - CD56
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
A chemotactic factor for neutrophils

45. What is a type I hypersensitivity reaction? What is atopic?
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
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
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
SP infections

46. in which immunodef order do you see a lot of pus? no pus?
Cross link
TGF beta and IL 10
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
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

47. Describe the complement independent Type II hypersenstivity reaction. Give an example.
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
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)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
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

48. Which are the only two antiinflammatory cytokines?
TGF beta and IL 10
IL 3; supports growth and differentiation of bone marrow stem cells
CD56
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

49. What are the autoantibodies for other vasculitides?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
IL 4 - 5 - 10 - 6
except hyperacute
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

50. where do NK cells develop?
Anti SS- A (anti RO) and Anti SS- B
Edema and necrosis in that region
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
Not thymus - BM