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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.
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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. Which disease is associated with DR7?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
CD56
Steroid responsive nephrotic syndrome
TGF beta and IL 10

2. In general What are T cells good for?
Negative nitroblue tetrazolium reduction test
Anti viral and anti tumor
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
NK cells

3. What are target cells?
Internal iliac
Active; passive - fast but short half life (3 weeks!)
Cells that stil have weird parts of their membrane that macrophages usually bite off
mesenchymal

4. What is the difference of IgE AIHA and IgG AIHA if they are both complement dependent type II hypersensitivities?
T cell activation; no with CD 4 or CD 8
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
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
IgE

5. In thymic development - What is the positive selection? negative selections?
When you select for which MHC it will have; take out the lymphs that self react
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
T cell dysfunction
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

6. Which diseases are associated with DR2?
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
Anti topoisomerase
MS - hay fever - SLE - goodpastures
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

7. What are the main symptoms of T cell immunodeficiencies?
Histamine; post capillary venules - vasodilation
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
C5a
Intracellular pathogens (acute and chronic viruses and virally induced cancers)

8. What are the cell surface proteins for Macrophages? which two are for opsonins?
Negative!
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
Alternative splicing of mRNA
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

9. What is the presentation of scid? treatment?
Edema and necrosis in that region
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Negative nitroblue tetrazolium reduction test
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

10. What is three common causes of severe combined immunodef? What is the result of all three?
heavy chains
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
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Paracortex; viral infection

11. What is the clinical use for azathioprine?
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
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
...
IgG

12. What are the autoantibodies for pernicious anemia?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Anti IF
Hemochromatosis
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

13. What lymph node drains the stomach?
Anti SS- A (anti RO) and Anti SS- B
Celiac
By transcytosis
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

14. 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)?
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Axillary
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
carboxy terminal

15. How does igA cross the epithelium?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
By transcytosis
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Activates Th1 helper cells; Macrophages

16. Only the _______ contribute to the Fc region
heavy chains
NK cells
Negative!
IgE

17. which of the hypersensitivity reactions is not Ab mediated?
IL 1 and IL 6
Anti smooth muscle
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Type IV

18. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
TGF beta and IL 10
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Para aortic

19. What does IL 2 do?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Activates cytotoxic CD 8 T cells as second signal
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
Th cells fail to produce interferon gamma; a lot of IgE

20. How is the thymus organized? what happens in each section?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
IgM and IgG
pale central germinal centers
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

21. What is passive immunity?
Receiving preformed Antibodies
Fc
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
IL 4 - 5 - 10 - 6

22. What lymph node drains the rectum (above the pectinate line)?
Internal iliac
S. aureus - E. Coli - aspergillus
Stimulate the liver to release acute phase reactants
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

23. How does the alternative pathway lead to MAC activation?
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
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)
T cell precursor
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

24. is IgM an opsonizer?
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
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!
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Negative!

25. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
Th cells fail to produce interferon gamma; a lot of IgE
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Thrombocytopenia
Anti IF

26. when can graft versus host disease? What is the result?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Anti glutamate carboxylase and anti insulin
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
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

27. What does granzyme do? who secretes it?
Its a serine protease that activates apoptosis; NK and CD8
IgG
2 heavy chains and two light chains
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

28. Describe complement dependent Type II hypersensitivity. Give an example.
Alternative splicing of mRNA
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
IL 5

29. what results in symptoms of shock in an acute hemolytic transfusion reaction?
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
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Anti IF

30. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
All MHC 1/CD8
Barrel hoop basement membrane fenestrations
isotype

31. What lymph node drains the lateral side of the dorsum of the foot?
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
MS
Anti glutamate carboxylase and anti insulin
Popliteal

32. IgM can exist as a _______ also
Anti alpha subunit 3 of collagen on type IV bm
Recom IL 11; thrombocytopenia
When you select for which MHC it will have; take out the lymphs that self react
pentamer

33. What are the sinusoids of the spleen? What is the difference between a spleen and a lymph node?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
The red pulp of the spleen its where the vasculature channels go through and interact with the parenchyma of the spleen (has macrophages) which empty in the sinuses; they are both encapsulated (with trabeculae) secondary lymphoid organs that trap ant
Anti smooth muscle
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

34. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Celiac
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
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

35. Which disease is associated with HLA A3?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Hemochromatosis
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Wiskott Aldrich syndrome

36. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
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
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
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

37. What are the major functions of Antibodies?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Receiving preformed Antibodies
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
...

38. which antibody activate mast cells - basophils - and eosinophils?
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!
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
S. aureus - E. Coli - aspergillus
IgE

39. What are the T cell functions?
Rheumatic arthritis
2 heavy chains and two light chains
Anti mitochondrial
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

40. What lymph node drains the anal canal (below the pectinate line)?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Superior mesenteric
Superficial inguinal

41. What is the receptor for EBV? On what cells is that located?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
A recomb cytokine of IL 2; RCC and metastatic melanoma
B - T - and NK cells

42. What is recomb alpha interferon used for?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
type four

43. What are the autoantibodies for autoimmune hepatitis?
Anti smooth muscle
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
Paracortex; viral infection
Activate macrophages

44. ________ regulate the cell mediated response.
RNA segment reassortment
Humoral
Anti U1 RNP (ribonucleoprotein)
...

45. What are the two signals required for T cells? what happens after?
Paracortex
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Antimicrosomal and antithyroglobulin

46. What lymph node drains the duodenum - jejunum?
Popliteal
Antibody mediated cytotoxicity; either complement dependent or complement independent
Superior mesenteric
T cell precursor

47. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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
Hereditary angioedema; PNH
Rheumatic arthritis

48. Which cytokines do Th2 release and For what?
Liver! (they are proteins circulating in the blood)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
IgM and IgA
Antimicrosomal and antithyroglobulin

49. What is recomb gamma interferon used for?
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
Chronic granulomatous disease
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 :(
IgM and IgG

50. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
TNF alpha and IL1
RNA segment reassortment
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Antibody mediated cytotoxicity; either complement dependent or complement independent