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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 part of the lymph node specifically expands during a cellular immune response? when would this occur?
IL 1 and IL 6
Anti viral and anti tumor
Paracortex; viral infection
No because no peptide fragment!

2. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
All MHC 1/CD8
pathogenesis

3. Name two endogenous pyrogens
Anti topoisomerase
Th2; Th1
IL 1 and IL 6
Anti smooth muscle

4. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
Antidesmoglein
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
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 viral and anti tumor

5. Describe the Mannose Lectin pathway
Carbohydrate
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
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Basophils! THey want IG E class switch!

6. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Cross link
RNA segment reassortment
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
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

7. What are the autoantibodies for Celiac disease?
MAC (membrane attack complex) Which is activated by C5b - C9 and results in lysis and cytoxicity by creating pores in the target membrane; encapsulated organisms (S. pnuemonia - H.influenzae - B perfussis for example) and other organisms with non pep
Lymphocytes
The patient could become cyanotic in the OR!
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)

8. What are MHC's necessary for? By themselves?
T cell precursor
Anti glutamate carboxylase and anti insulin
NK cells
T cell activation; no with CD 4 or CD 8

9. What are the main Cell surface proteins on T cells?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
CD56
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

10. IgG...
T cell activation; no with CD 4 or CD 8
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
opsonizes
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

11. Complements are...
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
acute phase reactants
encapsulated

12. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
MS
All MHC 1/CD8
Local infection/inflammation; infection of the ln itself; metastasis
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

13. IgM can fix complement but...
cannot cross placenta
secondary
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
dimer

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

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15. What is epo used for?
Anemias (esp due to renal failure)
pale central germinal centers
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

16. What lymph node drains the breast?
carboxy terminal
Axillary
dimer
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

17. 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?
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
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Pernicious Anemia and Hashimotos
Its a serine protease that activates apoptosis; NK and CD8

18. What are the two signals required for T cells? what happens after?
MHC I - CD16 - CD56
They directly stimulate Macrophages by binding CD14; also the alternative complement pathway binds to these host surfaces and induces MAC complex; also TLRs exist for endotoxins; also IgM though not an opsonin can act as a pentamer and trap the antig
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

19. which of the transplant rejections is antibody mediated? why does it occur?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
MS
Basophils! THey want IG E class switch!
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

20. 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?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
B - T - and NK cells
IgM
Basophils! THey want IG E class switch!

21. What is the autoantibody for SLE that is nonspecific? Specific?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Its main effect is a defect in Ab opsonization for killing
Local infection/inflammation; infection of the ln itself; metastasis
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

22. What bugs can actually infect the lymph node itself?
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
TNF alpha and IL1
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
No because no peptide fragment!

23. So antibodies are the effectors for the humoral response. List some of their functions.
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
opsonizes
dimer
IgG

24. Give three examples of bacteria that use antigenic variation and how.
Fc
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
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
The patient could become cyanotic in the OR!

25. What lymph node drains the scrotum?
Paracortex; viral infection
Superficial inguinal
B - T - and NK cells
Immunoflourescent staining of tissue biopsies

26. What are superantigens? give two examples.
opsonizes
Fc
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
Basophils! THey want IG E class switch!

27. What does CD16 on NK cells do?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Bind FcG for antibody dependent cellular cytotoxicity
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
CD56

28. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
All MHC 1/CD8
Cells that stil have weird parts of their membrane that macrophages usually bite off

29. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
T cell dysfunction
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
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

30. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
heavy chains
Alternative splicing of mRNA
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

31. Only the _______ contribute to the Fc region
Lymphocytes
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
active complement pathway
heavy chains

32. What is an example of a parasite showing antigenic variation?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
T
IgAs in mothers breast milk!
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

33. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Histamine; post capillary venules - vasodilation
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
dimer

34. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
...
B - T - and NK cells
Remove encapsulated bacateria
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

35. Which diseases are associated with DR5?
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Activates cytotoxic CD 8 T cells as second signal
Not thymus - BM
Pernicious Anemia and Hashimotos

36. IgE has the ___________ in the serum
Receiving preformed Antibodies
Anti IF
lowest concentration
False! B cell class switching requires a second signal

37. In order to produce Antibodies - does the antigen have to be phagocytosed? give an example with a bug and an autoimmune (type II hypersensitivity for example).
Type IV
Thrombocytopenia
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!
pathogenesis

38. what mediates the type II hypersensitivity? What are the two different methods?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Antibody mediated cytotoxicity; either complement dependent or complement independent
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
...

39. what ensure that a memory response is generated?
IgM and IgG
If there is class switching and plasma cell production (that is when memory cells are produced)
In the germinal center of secondary follicles (In the paler center)
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

40. Which disease is associated with DR7?
Antibody mediated cytotoxicity; either complement dependent or complement independent
Steroid responsive nephrotic syndrome
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
CD21 on B cells (although there is T cell lymphocytosis in EBV)

41. which of the hypersensitivity reactions is not Ab mediated?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Type IV
Anti glutamate carboxylase and anti insulin
Delayed type hypersensitivity

42. which cells have more complete tolerance - B or T cells?
Yes
Interferon gamma and IL 2
T
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

43. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Inferior mesenteric
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
Anti TSh receptor
Rheumatic arthritis

44. Which diseases are associated with DR4?
DM type I and RA
opsonizes
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
NK cells

45. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Th cells fail to produce interferon gamma; a lot of IgE
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Cross link
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)

46. How is the antigen loaded onto a MHC II?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Basophils! THey want IG E class switch!

47. What are the autoantibodies for graves?
Anti TSh receptor
opsonizes
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

48. where are complements produced?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
mesenchymal
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Liver! (they are proteins circulating in the blood)

49. What is the clinical use for sirolimus? what should you combine it with?
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
CRP - C3b - IgM
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Steroid responsive nephrotic syndrome

50. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Anti topoisomerase
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Activate macrophages
delayed!