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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 clinical use of Muromonab?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
T cell activation; no with CD 4 or CD 8
Immunosuppression after kidney transplantation
A - B - C; all the D's

2. What is thrombopoietin used for?
MHC I - CD16 - CD56
DM type I
Axillary
Thrombocytopenia

3. Describe the capsular structure of a lymph node; What are the functions of the LN?
pentamer
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
DM type I and RA
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

4. Which helper T cells' development is induced by IL 4? IL 12?
Th2; Th1
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
Influenza; antigenic shift; antigenic drift
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

5. What are the two signals to kill for NK cells?
A - B - C; all the D's
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Internal iliac
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

6. What is muromonab - CD3 (OKT3)
False! B cell class switching requires a second signal
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells

7. In general What are T cells good for?
Chronic granulomatous disease
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 viral and anti tumor
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

8. What is the toxicity of azathioprine?
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
...

9. What is immune complex disease? give an example.
Thrombocytopenia
A chemotactic factor for neutrophils
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
secondary

10. which B and T cell disorder presents with specifically low IgM?
pale central germinal centers
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Wiskott Aldrich syndrome
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

11. How does igA cross the epithelium?
pathogenesis
Barrel hoop basement membrane fenestrations
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
By transcytosis

12. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Anti TSh receptor
IgE; by activating eosinophils
Para aortic

13. The two heavy chains of an antibody contribute to the...
Fab portion
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
Antibody mediated cytotoxicity; either complement dependent or complement independent
Humoral

14. What is recomb gamma interferon used for?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
active complement pathway
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Chronic granulomatous disease

15. What lymph node drains the scrotum?
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
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Internal iliac
Superficial inguinal

16. ________ regulate the cell mediated response.
IgM and IgD
No because no peptide fragment!
Anti Jo -1
Humoral

17. What is the receptor for EBV? On what cells is that located?
Bind FcG for antibody dependent cellular cytotoxicity
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
CD21 on B cells (although there is T cell lymphocytosis in EBV)
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

18. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
Antihistone
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
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

19. What is the marginal zone of the spleen? what happens there?
Inferior mesenteric
Antidesmoglein
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
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

20. What are the autoantibodies for Celiac disease?
Acts as second signal on B cells to induce class switching to IgE and IgG
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Axillary
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

21. Only the _______ contribute to the Fc region
heavy chains
Hemochromatosis
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Chronic granulomatous disease

22. What does granzyme do? who secretes it?
Superficial inguinal
All MHC 1/CD8
Its a serine protease that activates apoptosis; NK and CD8
Cells that stil have weird parts of their membrane that macrophages usually bite off

23. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Cross link
mesenchymal

24. Give three examples of bacteria that use antigenic variation and how.
MHC class molecules bind to KIRS or CD94 to prevent killing
pale central germinal centers
Thrombocytopenia
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein

25. which of the hypersensitivity reactions is not Ab mediated?
Para aortic
MHC I - CD16 - CD56
Antidesmoglein
Type IV

26. Which MHC presents intracellular peptides? how so?
Cross link
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Anti Jo -1
MHC I; from RER with help of the B2 microglobulin

27. what results in symptoms of shock in an acute hemolytic transfusion reaction?
cannot cross placenta
Complement activation (active in both)
Inferior mesenteric
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

28. Which disease is associated with DR7?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Steroid responsive nephrotic syndrome
SP infections
lowest concentration

29. What is recomb alpha interferon used for?
If there is class switching and plasma cell production (that is when memory cells are produced)
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
IgG

30. What does IL 10 do? who is secreted by?
Interferon gamma and IL 2
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
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
CD56

31. What is the presentation of scid? treatment?
Cells that stil have weird parts of their membrane that macrophages usually bite off
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
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
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

32. How do you test for chronic granulomatous disease?
Axillary
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
The patient could become cyanotic in the OR!
Negative nitroblue tetrazolium reduction test

33. which type of immunity is slow but long lasting? as opposed to...
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
Active; passive - fast but short half life (3 weeks!)
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

34. The Fc region is found on the...
Th2; Th1
carboxy terminal
IL 4 - 5 - 10 - 6
Superficial inguinal

35. Type Iv hypersensitivity is...
delayed!
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
acute phase reactants
IgM and IgG

36. So antibodies are the effectors for the humoral response. List some of their functions.
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
Delayed type hypersensitivity
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

37. How do you test for type III hypersensitivity?
Immunoflourescent staining of tissue biopsies
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
mesenchymal
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

38. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
CD56
TNF alpha and IL1
Influenza; antigenic shift; antigenic drift

39. What does IL 4 do?
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
Acts as second signal on B cells to induce class switching to IgE and IgG
Antidesmoglein
Anti Ach receptor

40. What is the general structure of an Ab?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
2 heavy chains and two light chains
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
Paracortex; viral infection

41. What lymph node drains the testes?
Para aortic
S. aureus - E. Coli - aspergillus
Rheumatic arthritis
DM type I

42. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
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
Liver! (they are proteins circulating in the blood)
Anti IF
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

43. What does interferon gamma do to be antiviral?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Popliteal
Increases expression of MHC I and MHC II and also activates NK cells
Hemochromatosis

44. What happens when a T helper cell in the paracortical section encounters an antigen? a cytotoxic t cell? a B cell in the cortical section?
Axillary
An antigen encounter (presented by APC for Th2) with Th2 will result in it to go to the cortical section and help with B cell activation; Cytotoxic T cell will enter vasculature/efferent lymph to go kill; B cell will wait for Th2 for activation and t
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
IL 1 and IL 6

45. 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)?
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
Popliteal
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

46. can igG cross the placenta?
Tetanus - Botulinum - HBV - Rabies
No because no peptide fragment!
Receiving preformed Antibodies
Yes

47. How is the thymus organized? what happens in each section?
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
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Superficial inguinal

48. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Cross link
Kill them because they have CD16 on them that recognize the FcG portion
Influenza; antigenic shift; antigenic drift
Anti Jo -1

49. What is the mode of inheritance of Chediak Higashi syndrome? What is the disease d/t? What does it result in? What is the presentation?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Wiskott Aldrich syndrome
Superficial inguinal
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

50. What are the main Cell surface proteins on T cells?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Popliteal
IL 4 - 5 - 10 - 6
MS - hay fever - SLE - goodpastures