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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. What are superantigens? give two examples.
Type IV
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
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

2. What is the marginal zone of the spleen? what happens there?
Severe pyogenic infections early in life
Viral neutralization of igM and IgG!
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
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

3. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
TNF alpha and IL1
carboxy terminal
Not thymus - BM
Edema and necrosis in that region

4. What is the clinical use of Muromonab?
B - T - and NK cells
Immunosuppression after kidney transplantation
CRP - C3b - IgM
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

5. 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?
Lymphocytes
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
cannot cross placenta

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

7. What is the pathology in hyperacute transplant rejection?
Antimicrosomal and antithyroglobulin
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

8. In thymic development - What is the positive selection? negative selections?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
When you select for which MHC it will have; take out the lymphs that self react
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Negative!

9. Which is the main antibody in the delayed or secondary response to an antigen?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
IgG
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
Type II hypersensitivity - complement dependent resulting in phagocytosis of RBCs coated with C3b by fixed macrophages in the spleen; Group O mother has anti A - B - IgG Abs that cross placenta and attach to fetal blood group A or B RBCs

10. what prevents NK cells from killing normal cells if their default is to kill?
MHC class molecules bind to KIRS or CD94 to prevent killing
If there is class switching and plasma cell production (that is when memory cells are produced)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Alternative splicing of mRNA

11. What is the toxicity of muromonab?
A recomb cytokine of IL 2; RCC and metastatic melanoma
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Barrel hoop basement membrane fenestrations
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

12. What cytokines to Th2 secrete?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Interferon gamma and IL 2
Its a serine protease that activates apoptosis; NK and CD8
IL 4 - 5 - 10 - 6

13. where are complements produced?
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
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Liver! (they are proteins circulating in the blood)

14. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
encapsulated
Activate macrophages
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

15. What are the cell surface proteins for Macrophages? which two are for opsonins?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
T
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Bind FcG for antibody dependent cellular cytotoxicity

16. What lymph node drains the rectum (above the pectinate line)?
Internal iliac
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Recom IL 11; thrombocytopenia

17. Which disease is associated with DR7?
Steroid responsive nephrotic syndrome
A recomb cytokine of IL 2; RCC and metastatic melanoma
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Lymphocytes

18. What are the autoantibodies for drug induced lupus?
Antihistone
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Axillary
S. aureus - E. Coli - aspergillus

19. What are the autoantibodies for other vasculitides?
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Anti IF
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

20. Which disease is associated with DR3?
DM type I
C5a
Carbohydrate
Cytokine IL 10 secreted by Th2

21. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Humoral
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Sinusitis - otitis media - pneumonia
IL 15; IL 12 - interferon Beta and interferon alpha

22. What is the presentation of Brutons agammaglobulinemia?
except hyperacute
Negative selection
An acidified endosome with the antigen fuses with the MHC which causes the release of the invariant chain Which is sitting in spot of antigen and stabilizing the MHC II
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

23. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
Negative!
CD56
pathogenesis
...

24. What lymph node drains the upper limb?
DM type I and RA
IgE; by activating eosinophils
Axillary
A chemotactic factor for neutrophils

25. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
Fc
Active; passive - fast but short half life (3 weeks!)
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
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

26. Complements are...
acute phase reactants
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

27. What are the two signals required for T cells? what happens after?
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
NK cells
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Anti U1 RNP (ribonucleoprotein)

28. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Anti glutamate carboxylase and anti insulin
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
not Ab mediated

29. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Anti U1 RNP (ribonucleoprotein)
carboxy terminal

30. What are the two signals required for Th1 cells? what happens after then activated?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Anti Jo -1
If there is class switching and plasma cell production (that is when memory cells are produced)
cannot cross placenta

31. What is the treatment of acute transplant rejection?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Cyclosporine - OKT3
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Superior mesenteric

32. What are the T cell functions?
Inferior mesenteric
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

33. What is colostrum?
Internal iliac
The igA found in breast milk
Anti viral and anti tumor
Immunoflourescent staining of tissue biopsies

34. IgE has the ___________ in the serum
acute phase reactants
lowest concentration
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Activates Th1 helper cells; Macrophages

35. What is the cause of thymic aplasia? What is its presentation? What are the labs?
By transcytosis
Antimicrosomal and antithyroglobulin
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
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

36. Which are the only two antiinflammatory cytokines?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
TGF beta and IL 10
All MHC 1/CD8
Carbohydrate

37. Which antibodies can be multimeric?
Anti IF
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
IgM and IgA
T cell activation; no with CD 4 or CD 8

38. What are the two signals required for B cell class switching? Which is the second signal?
A recomb cytokine of IL 2; RCC and metastatic melanoma
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Axillary
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

39. Which diseases are associated with DR4?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
DM type I and RA
Fab portion
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

40. IgG...
IgA
T cell activation; no with CD 4 or CD 8
opsonizes
Alternative splicing of mRNA

41. which cells have more complete tolerance - B or T cells?
Remove encapsulated bacateria
Cells that stil have weird parts of their membrane that macrophages usually bite off
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
T

42. What does IL 2 do?
Carbohydrate
Activates cytotoxic CD 8 T cells as second signal
MHC II - B7
Negative nitroblue tetrazolium reduction test

43. What is Aldesleukin? What is it used for
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
A recomb cytokine of IL 2; RCC and metastatic melanoma
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation

44. To what portion of the Antibody do the complements bind?
Fc
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
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Axillary

45. what characterizes an arthus reaction?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Edema and necrosis in that region
Anti U1 RNP (ribonucleoprotein)
2 heavy chains and two light chains

46. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
T cell precursor
MS - hay fever - SLE - goodpastures
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Histamine; post capillary venules - vasodilation

47. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
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
Histamine; post capillary venules - vasodilation
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
CRP - C3b - IgM

48. What does interferon gamma do to be antiviral?
Increases expression of MHC I and MHC II and also activates NK cells
TLR ad nuclear receptors
C5a
Rheumatic arthritis

49. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
MHC I - CD16 - CD56
IgG
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)

50. What is the pathogenesis of acute transplant rejection? When does it occur?
Carbohydrate
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
MS - hay fever - SLE - goodpastures
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after