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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. Describe complement dependent Type II hypersensitivity. Give an example.
Anti mitochondrial
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
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like 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

2. What is digoxin immune Fab used for?
Inferior mesenteric
...
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Antidote for digoxin intoxication

3. What is Aldesleukin? What is it used for
A recomb cytokine of IL 2; RCC and metastatic melanoma
T cell dysfunction
CD56
Recom IL 11; thrombocytopenia

4. What does it mean if there are igM in the serum at birth?
Local infection/inflammation; infection of the ln itself; metastasis
All MHC 1/CD8
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

5. Which HLA's are included in MHC I? MHC II?

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6. Type IV hypersensitivity is i...
not Ab mediated
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
No because no peptide fragment!
Antidesmoglein

7. Which disease is associated with DR3?
Secretory component
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
DM type I
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

8. What is the main cytokine released by T cells? What does it do
IL 3; supports growth and differentiation of bone marrow stem cells
except hyperacute
Local infection/inflammation; infection of the ln itself; metastasis
IgM and IgD

9. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Complement activation (active in both)
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 mitochondrial

10. What does Interferon alpha and beta do? how?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
When you select for which MHC it will have; take out the lymphs that self react
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

11. What is the mechanism for sirolimus? what else it known as?
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
Humoral
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells

12. Which disease is associated withB B27?
Hereditary angioedema; PNH
pentamer
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
2 heavy chains and two light chains

13. To what portion of the Antibody do the complements bind?
IgE; by activating eosinophils
Fc
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
IgM and IgG

14. Describe the complement independent Type II hypersenstivity reaction. Give an example.
cannot cross placenta
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

15. What do multimeric antibodies require for assembly?
A j chain
IgA
IgM and IgG
except hyperacute

16. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
TGF beta and IL 10
IL 4
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Influenza; antigenic shift; antigenic drift

17. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
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
No because no peptide fragment!
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

18. What is the presentation of Brutons agammaglobulinemia?
CROSS LINK Beta region on TCR of CD4 cells to the MHC class II on APCs this results in uncoordinated release of Interferon gamma from CD4 Th1 cells and subsequent release of IL1 - IL6 and TNF alpha from Macrophages --> toxic shock syndrome; s. pyogen
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
2 heavy chains and two light chains
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

19. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Alternative splicing of mRNA
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
pathogenesis

20. are Th cells involved in trapping of antigens of endotoxin/LPS?
Viral neutralization of igM and IgG!
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
No because no peptide fragment!
Celiac

21. in which immunodef order do you see a lot of pus? no pus?
Edema and necrosis in that region
Anti topoisomerase
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Immunosuppression after kidney transplantation

22. IgE has the ___________ in the serum
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Anti SS- A (anti RO) and Anti SS- B
lowest concentration
IgA

23. How is i Th1 helper cell inhibited?
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
IgAs in mothers breast milk!
Cytokine IL 10 secreted by Th2
A chemotactic factor for neutrophils

24. What is the pathogenesis of acute transplant rejection? When does it occur?
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
The patient could become cyanotic in the OR!
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after

25. How do you test for type III hypersensitivity?
Immunoflourescent staining of tissue biopsies
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
TLR ad nuclear receptors
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

26. If an antigen lacks a peptide component How does the adaptive immunity attack it? What type of response is this called. give an example of bugs that do this. what implications does this have on splenectomy?
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
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Thrombocytopenia
Increases expression of MHC I and MHC II and also activates NK cells

27. What is the pathology of acute transplant rejection? is it reversible?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
IgA
A recomb cytokine of IL 2; RCC and metastatic melanoma
secondary

28. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Not thymus - BM
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
A chemotactic factor for neutrophils

29. ________ regulate the cell mediated response.
Acts as second signal on B cells to induce class switching to IgE and IgG
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Humoral
RNA segment reassortment

30. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
pathogenesis
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
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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

31. What are the cell surface proteins on NK cells?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Anti viral and anti tumor
MHC I - CD16 - CD56
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

32. What is the clinical use of Muromonab?
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Immunosuppression after kidney transplantation
pale central germinal centers
Axillary

33. What is the pathology in hyperacute transplant rejection?
Antidesmoglein
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Glycoproteins; HLA
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

34. What is the toxicity of azathioprine?
Histamine; post capillary venules - vasodilation
Carbohydrate
...
T cell activation; no with CD 4 or CD 8

35. what cell surface proteins are on all APCs?
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
encapsulated
MHC II - B7
Remove encapsulated bacateria

36. What lymph node drains the sigmoid colon?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
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
Complement activation (active in both)
Inferior mesenteric

37. What lymph node drains the upper limb?
IgM
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Anti TSh receptor
Axillary

38. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
Anti alpha subunit 3 of collagen on type IV bm
cannot cross placenta
Complement activation (active in both)

39. What type of side chains are found on Fc region of an antibody?
IgM and IgD
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
Carbohydrate
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

40. Monomer in circulation - ___ when secreted
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
dimer
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

41. What is the late phase reaction of anaphylaxis allergy? what mediates it?
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)
Activate macrophages
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!
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

42. What is wiskott aldrich syndrome? What is its mode of inheritance? What is the pathogenesis of disease? What is its triad of presentation? what labs does it present with?
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
Graves
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
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

43. which B and T cell disorder presents with specifically low IgM?
Anti topoisomerase
IgAs in mothers breast milk!
Wiskott Aldrich syndrome
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

44. In general What are T cells good for?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
lowest concentration
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Anti viral and anti tumor

45. which interleukin receptor is required for NK development? activation?
Immunoflourescent staining of tissue biopsies
Activate macrophages
IL 15; IL 12 - interferon Beta and interferon alpha
Not thymus - BM

46. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Cross link
RNA segment reassortment

47. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
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
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Paracortex; viral infection

48. What lymph node drains the thigh?
IL 15; IL 12 - interferon Beta and interferon alpha
Superficial inguinal
Humoral
The patient could become cyanotic in the OR!

49. What are the cell surface proteins for Macrophages? which two are for opsonins?
Anti Jo -1
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
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
Humoral

50. Which antibodies can be multimeric?
Antidesmoglein
IgM and IgA
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Anti smooth muscle