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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.
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. IgM can fix complement but...
Cells that stil have weird parts of their membrane that macrophages usually bite off
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
cannot cross placenta
TGF beta and IL 10

2. What is passive immunity?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Receiving preformed Antibodies
Antihistone
not Ab mediated

3. What is the presentation of Brutons agammaglobulinemia?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Superior mesenteric

4. What is the pathology seen in chronic transplant rejection?
TNF alpha and IL1
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Paracortex; viral infection

5. What lymph node drains the sigmoid colon?
B - T - and NK cells
Inferior mesenteric
Increases expression of MHC I and MHC II and also activates NK 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

6. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
pathogenesis
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
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
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

7. Which diseases are associated with DR4?
MHC class molecules bind to KIRS or CD94 to prevent killing
DM type I and RA
Cytokine IL 10 secreted by Th2
Anti topoisomerase

8. What lymph node drains the breast?
The igA found in breast milk
Increases expression of MHC I and MHC II and also activates NK cells
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Axillary

9. The MALT/GALT are not...
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
encapsulated
The igA found in breast milk
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

10. What are the autoantibodies for wegeners granulomatosis?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
CD56
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
IgAs in mothers breast milk!

11. What kinds of receptors activate innate immunity?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
cannot cross placenta
TLR ad nuclear receptors
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

12. which of the hypersensitivity reactions is not Ab mediated?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Type IV
mesenchymal
Lymphocytes

13. What is the pathology of acute transplant rejection? is it reversible?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
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
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

14. what will NK cells do to cells covered in IgG Ab? why?
False! B cell class switching requires a second signal
Kill them because they have CD16 on them that recognize the FcG portion
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
IL 4

15. What cytokines are released by Th1 cells?
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
Interferon gamma and IL 2
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
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

16. What happens in a secondary follicle?
IgM and IgG
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

17. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Antidesmoglein
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Influenza; antigenic shift; antigenic drift

18. In general What are T cells good for?
Hereditary angioedema; PNH
Anti viral and anti tumor
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
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

19. What portion of the lymph node is not well developed in DiGeorge Syndrome?
Th cells fail to produce interferon gamma; a lot of IgE
Tetanus - Botulinum - HBV - Rabies
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 :(
Paracortex

20. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Its a serine protease that activates apoptosis; NK and CD8
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Histamine; post capillary venules - vasodilation
...

21. other than eat and bite RBCs what else do Macrophages of spleen do>
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
2 heavy chains and two light chains
Remove encapsulated bacateria
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

22. What are the symptoms of serum sickness?
dimer
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Fab portion

23. What are the autoantibodies for autoimmune hepatitis?
Anti smooth muscle
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
pathogenesis

24. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
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 :(
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 alpha subunit 3 of collagen on type IV bm

25. Which antibody mediates immunity to worms? how?
Yes
IgE; by activating eosinophils
No because no peptide fragment!
Glycoproteins; HLA

26. What is the clinical use of Muromonab?
Kill them because they have CD16 on them that recognize the FcG portion
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Immunosuppression after kidney transplantation

27. What does granzyme do? who secretes it?
Its a serine protease that activates apoptosis; NK and CD8
TGF beta and IL 10
pale central germinal centers
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

28. what characterizes an arthus reaction?
Alternative splicing of mRNA
Edema and necrosis in that region
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
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

29. The idiotype; the Fc portion determines the...
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
isotype
Carbohydrate
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

30. What is the cause of thymic aplasia? What is its presentation? What are the labs?
Viral neutralization of igM and IgG!
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
not Ab mediated
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

31. which antibody is involved in the primary response or immediate response to an antigen?
isotype
Axillary
active complement pathway
IgM

32. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Barrel hoop basement membrane fenestrations
IgG
IL 15; IL 12 - interferon Beta and interferon alpha

33. What is the difference of IgE AIHA and IgG AIHA if they are both complement dependent type II hypersensitivities?
IgG
cannot cross placenta
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
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

34. What does Interferon alpha and beta do? how?
Viral neutralization of igM and IgG!
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Humoral

35. What is the pathology in hyperacute transplant rejection?
Anti IF
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
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

36. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
2 heavy chains and two light chains
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Cross link
Macrophages - Dendritic cells - B cells

37. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
pentamer
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
secondary
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

38. The ______ in the BM are DN - the DP are in the cortex of thymus
Alternative splicing of mRNA
dimer
T cell precursor
Cells that stil have weird parts of their membrane that macrophages usually bite off

39. What is serum sickness? give an example.
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
IgG
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

40. What is the general structure of an Ab?
TLR ad nuclear receptors
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
A chemotactic factor for neutrophils
2 heavy chains and two light chains

41. Which disease is associated with HLA A3?
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
2 heavy chains and two light chains
Celiac
Hemochromatosis

42. What does IgA pick up from epithelial cells before being secreted?
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Secretory component
Paracortex
Stimulate the liver to release acute phase reactants

43. What is anergy? why does this occur?
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
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Previous transfusion; pregnant woman whose fetus had paternal antigens
Interferon gamma and IL 2

44. What is muromonab - CD3 (OKT3)
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
Carbohydrate
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

45. What are the autoantibodies for pernicious anemia?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Anti IF

46. What is recomb alpha interferon used for?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
neutrophilia!
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

47. What are the main Cell surface proteins on T cells?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH 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 :(
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

48. The two heavy chains of an antibody contribute to the...
Basophils! THey want IG E class switch!
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Fab portion
Antidote for digoxin intoxication

49. where do somatic hypermutation and class switching occur?
A chemotactic factor for neutrophils
In the germinal center of secondary follicles (In the paler center)
Anti glutamate carboxylase and anti insulin
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

50. What are the cell surface proteins on NK cells?
Some microbial surfaces (only) have mannan binding lectin which activates a protease that cleaves C2 and C4 which combine to make C3. the rest follows the alternative pathway
IL 1 and IL 6
MHC I - CD16 - CD56
Stimulate the liver to release acute phase reactants