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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. So antibodies are the effectors for the humoral response. List some of their functions.
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

2. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
Superior mesenteric
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

3. What happens in a secondary follicle?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
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
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Macrophages - Dendritic cells - B cells

4. What is three common causes of severe combined immunodef? What is the result of all three?
Receiving preformed Antibodies
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
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
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

5. where do somatic hypermutation and class switching occur?
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
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
In the germinal center of secondary follicles (In the paler center)
T cell dysfunction

6. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
Daclizumab; prevent ACUTE rejection of renal transplant
A recomb cytokine of IL 2; RCC and metastatic melanoma
TNF alpha and IL1
Superficial inguinal

7. What does IL 5 do?
Anti U1 RNP (ribonucleoprotein)
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Axillary

8. can igG cross the placenta?
Yes
CD56
Receiving preformed Antibodies
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

9. What is passive immunity?
Barrel hoop basement membrane fenestrations
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
False! B cell class switching requires a second signal
Receiving preformed Antibodies

10. 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?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Graves
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

11. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
2 heavy chains and two light chains
MS
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

12. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
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
Internal iliac
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after

13. 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
dimer
Axillary
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

14. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Wiskott Aldrich syndrome
Anti mitochondrial
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

15. The secondary follicles have __________; primary follicles are dense
Graves
pale central germinal centers
2 heavy chains and two light chains
dimer

16. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
Active; passive - fast but short half life (3 weeks!)
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
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

17. What lymph node drains the duodenum - jejunum?
Viral neutralization of igM and IgG!
Yes
heavy chains
Superior mesenteric

18. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
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
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
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
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class

19. Give an example of someone who could get hyperacute transplant rejection.
Graves
Previous transfusion; pregnant woman whose fetus had paternal antigens
Immunoflourescent staining of tissue biopsies
Pernicious Anemia and Hashimotos

20. What are target cells?
Cells that stil have weird parts of their membrane that macrophages usually bite off
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
False! B cell class switching requires a second signal
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

21. 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)?
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
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
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Glycoproteins; HLA

22. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Negative nitroblue tetrazolium reduction test
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Th cells fail to produce interferon gamma; a lot of IgE
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

23. The MALT/GALT are not...
Immunoflourescent staining of tissue biopsies
Anemias (esp due to renal failure)
encapsulated
T

24. What is the main function of TNF alpha? How does it do this?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
pentamer
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
IgE

25. How do you test for chronic granulomatous disease?
Negative nitroblue tetrazolium reduction test
Its a serine protease that activates apoptosis; NK and CD8
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
Anti TSh receptor

26. Describe complement dependent Type II hypersensitivity. Give an example.
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
2 heavy chains and two light chains
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
carboxy terminal

27. How is sirolimus different from tacrolimus?
Antihistone
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
IL 4 - 5 - 10 - 6

28. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
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
lowest concentration
Antibody mediated cytotoxicity; either complement dependent or complement independent
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

29. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
DM type I and RA
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
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
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

30. What is the toxicity of azathioprine?
Th2; Th1
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
...
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

31. What is the receptor for EBV? On what cells is that located?
Antihistone
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
CRP - C3b - IgM
CD21 on B cells (although there is T cell lymphocytosis in EBV)

32. What is digoxin immune Fab used for?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Antibody mediated cytotoxicity; either complement dependent or complement independent
Antidote for digoxin intoxication
Not thymus - BM

33. in which immunodef order do you see a lot of pus? no pus?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Anti SS- A (anti RO) and Anti SS- B
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

34. 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)
Anti IF
Viral neutralization of igM and IgG!
Inferior mesenteric

35. Which antibodies can be multimeric?
DM type I
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
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
IgM and IgA

36. A lymph node is a ________ lymphoid organ.
CD56
IgG
secondary
IgM and IgA

37. when can graft versus host disease? What is the result?
IgM and IgD
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
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
Hemochromatosis

38. What type of fenestrations are found in the red pulp of the spleen?
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
...
Barrel hoop basement membrane fenestrations

39. which antibody is involved in the primary response or immediate response to an antigen?
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
IgM
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
TNF alpha and IL1

40. What are the three types of APCs?
MHC I - CD16 - CD56
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Stimulate the liver to release acute phase reactants
Macrophages - Dendritic cells - B cells

41. which cytokine inhibits TH2 cells? secreted by who?
Interferon gamma; Th1
Remove encapsulated bacateria
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
CRP - C3b - IgM

42. What is the monoclonal antibody to IL2 on activated T cells? What is it used for?
IL 4
IgM and IgA
isotype
Daclizumab; prevent ACUTE rejection of renal transplant

43. what happens in a deficiency of C1 esterase inhibitor? DAF?
Histamine; post capillary venules - vasodilation
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Hereditary angioedema; PNH

44. The pathogenesis of contact dermatitis is ________ hypersensitivity
type four
B - T - and NK cells
IgG
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

45. what cytokine does basophils secrete?
IL 4
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
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
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

46. which cells have more complete tolerance - B or T cells?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
T

47. Describe the capsular structure of a lymph node; What are the functions of the LN?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Anemias (esp due to renal failure)

48. What is the common variable immunodeficiency ? How is it different from Brutons?
IgG
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
B - T - and NK cells
Secretory component

49. Which antibody mediates immunity to worms? how?
Antidesmoglein
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
IgE; by activating eosinophils
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

50. What are the autoantibodies for autoimmune hepatitis?
Anti smooth muscle
Fc
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy