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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 happens when a T helper cell in the paracortical section encounters an antigen? a cytotoxic t cell? a B cell in the cortical section?
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
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Delayed type hypersensitivity

2. Give three examples of bacteria that use antigenic variation and how.
Anti glutamate carboxylase and anti insulin
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IL 5
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

3. what prevents NK cells from killing normal cells if their default is to kill?
Activates cytotoxic CD 8 T cells as second signal
MHC class molecules bind to KIRS or CD94 to prevent killing
carboxy terminal
DM type I and RA

4. What is the monoclonal antibody to IL2 on activated T cells? What is it used for?
Cytokine IL 10 secreted by Th2
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
Para aortic
Daclizumab; prevent ACUTE rejection of renal transplant

5. Which is the main antibody that provides passive immunity to infants?
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
IgG
Cyclosporine - OKT3
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

6. 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
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Remove encapsulated bacateria
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

7. What lymph node drains the upper limb?
Axillary
Carbohydrate
Antidote for digoxin intoxication
Yes

8. Describe the complement independent Type II hypersenstivity reaction. Give an example.
T cell precursor
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
A chemotactic factor for neutrophils

9. What are the autoantibodies for type I diabetes mellitus?
A - B - C; all the D's
Anti glutamate carboxylase and anti insulin
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
Anti TSh receptor

10. What are four results of a splenectomy?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
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
IgM

11. What does granulysin do?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
IgE; by activating eosinophils
Lymphocytes
lowest concentration

12. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
T cell dysfunction
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Graves
Superior mesenteric

13. What are some sinopulmonary infections?
pale central germinal centers
Sinusitis - otitis media - pneumonia
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
...

14. 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
Remove encapsulated bacateria
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

15. What lymph node drains the testes?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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
Anti viral and anti tumor
Para aortic

16. which cells have more complete tolerance - B or T cells?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Active; passive - fast but short half life (3 weeks!)
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
T

17. 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 III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
pale central germinal centers
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!

18. What does IL 5 do?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
A chemotactic factor for neutrophils
Antimicrosomal and antithyroglobulin
Secretory component

19. What is muromonab - CD3 (OKT3)
Its a serine protease that activates apoptosis; NK and CD8
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
not Ab mediated

20. T/F B cells do not require a second signal
False! B cell class switching requires a second signal
Secretory component
RNA segment reassortment
Anti SS- A (anti RO) and Anti SS- B

21. which cytokine inhibits TH2 cells? secreted by who?
IgA
Interferon gamma; Th1
Paracortex
delayed!

22. 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?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
T
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

23. What is the pathogenesis of a candida skin test?
Antihistone
Recom IL 11; thrombocytopenia
Delayed type hypersensitivity
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

24. 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)
IgG
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
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

25. Which are the only two antiinflammatory cytokines?
TGF beta and IL 10
Anti Ach receptor
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

26. 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)?
Anti U1 RNP (ribonucleoprotein)
A j chain
Negative selection
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

27. What part of the lymph node specifically expands during a cellular immune response? when would this occur?
Paracortex; viral infection
B - T - and NK cells
Activate macrophages
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

28. What are the autoantibodies for systemic sclerosis?
T cell precursor
IL 15; IL 12 - interferon Beta and interferon alpha
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 topoisomerase

29. What are the PALS?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
T cell precursor
carboxy terminal
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

30. which antibodies can bind complement?
T cell activation; no with CD 4 or CD 8
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
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
IgM and IgG

31. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
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
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Complement activation (active in both)

32. The ______ in the BM are DN - the DP are in the cortex of thymus
mesenchymal
T cell precursor
IgM and IgA
Delayed type hypersensitivity

33. What is the pathology of acute transplant rejection? is it reversible?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Not thymus - BM
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
DM type I

34. What lymph node drains the duodenum - jejunum?
Superior mesenteric
Anti U1 RNP (ribonucleoprotein)
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
Antibody mediated cytotoxicity; either complement dependent or complement independent

35. Which type of selection of thymic development provides central tolerance?
Negative selection
Superficial inguinal
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Basophils! THey want IG E class switch!

36. Which is the main antibody in the delayed or secondary response to an antigen?
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
Kill them because they have CD16 on them that recognize the FcG portion
Liver! (they are proteins circulating in the blood)
IgG

37. What lymph node drains the thigh?
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Superficial inguinal
Axillary
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

38. What is the clinical use for azathioprine?
Receiving preformed Antibodies
Wiskott Aldrich syndrome
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
...

39. What lymph node drains the anal canal (below the pectinate line)?
Yes
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Remove encapsulated bacateria
Superficial inguinal

40. What is anergy? why does this occur?
cannot cross placenta
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

41. What are the autoantibodies for hashimotos?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Sinusitis - otitis media - pneumonia
Antimicrosomal and antithyroglobulin
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

42. What are the autoantibodies for autoimmune hepatitis?
Anti smooth muscle
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
DM type I and RA
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

43. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
All MHC 1/CD8
C5a
The patient could become cyanotic in the OR!
Negative!

44. How is i Th1 helper cell inhibited?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Cytokine IL 10 secreted by Th2
except hyperacute

45. What are the autoantibodies for polymyositis and dermatomyositis?
Antimicrosomal and antithyroglobulin
Anti Jo -1
Antidote for digoxin intoxication
Increases expression of MHC I and MHC II and also activates NK cells

46. What are the labs in brutons agammaglobulinemia?
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
Thrombocytopenia
Anti U1 RNP (ribonucleoprotein)
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class

47. A lymph node is a ________ lymphoid organ.
secondary
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Para aortic

48. How does igA cross the epithelium?
Pernicious Anemia and Hashimotos
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
Negative selection
By transcytosis

49. what bacteria are a splenectomy patient most susceptible to? why?
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
Severe pyogenic infections early in life
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
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 :(

50. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Negative!