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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. Leukocyte adhesion defect presents with...
TLR ad nuclear receptors
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
Daclizumab; prevent ACUTE rejection of renal transplant
neutrophilia!

2. What lymph node drains the lateral side of the dorsum of the foot?
Popliteal
Remove encapsulated bacateria
No because no peptide fragment!
Internal iliac

3. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
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
Antimicrosomal and antithyroglobulin
Graves
Chronic granulomatous disease

4. In general What are T cells good for?
Antibody mediated cytotoxicity; either complement dependent or complement independent
All MHC 1/CD8
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Anti viral and anti tumor

5. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
IL 5
Increases expression of MHC I and MHC II and also activates NK cells
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
not Ab mediated

6. Name the three opsonins
CRP - C3b - IgM
The igA found in breast milk
cannot cross placenta
Sinusitis - otitis media - pneumonia

7. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Antidote for digoxin intoxication
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
MHC I; from RER with help of the B2 microglobulin

8. What bugs can actually infect the lymph node itself?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Viral neutralization of igM and IgG!
IL 5

9. Other than stimulating fever - what else does IL 6 do?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Cyclosporine - OKT3
Stimulate the liver to release acute phase reactants

10. What is the main function of IL 8?
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
A chemotactic factor for neutrophils
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
Superficial inguinal

11. What are the function of B cells?
Anemias (esp due to renal failure)
IgAs in mothers breast milk!
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

12. A lymph node is a ________ lymphoid organ.
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
carboxy terminal
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
secondary

13. ________ regulate the cell mediated response.
Humoral
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
opsonizes
Cytokine IL 10 secreted by Th2

14. 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?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
...
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
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

15. What does CD16 on NK cells do?
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
IgM and IgA
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Bind FcG for antibody dependent cellular cytotoxicity

16. What are the two signals required for B cell class switching? Which is the second signal?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
MHC I - CD16 - CD56

17. Describe complement dependent Type II hypersensitivity. Give an example.
Celiac
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
cannot cross placenta
MHC I - CD16 - CD56

18. what secretes IL 4?
Basophils! THey want IG E class switch!
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (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

19. where are complements produced?
Antimicrosomal and antithyroglobulin
Anti glutamate carboxylase and anti insulin
Liver! (they are proteins circulating in the blood)
Delayed type hypersensitivity

20. The ______ in the BM are DN - the DP are in the cortex of thymus
Cross link
T cell precursor
type four
False! B cell class switching requires a second signal

21. What is recomb alpha interferon used for?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
heavy chains
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

22. what happens in a deficiency of C1 esterase inhibitor? DAF?
Anti smooth muscle
Antimicrosomal and antithyroglobulin
Hereditary angioedema; PNH
2 heavy chains and two light chains

23. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
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
MHC I - CD16 - CD56
IL 15; IL 12 - interferon Beta and interferon alpha

24. From where do cytokines come from?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
pathogenesis
Lymphocytes

25. What cytokines to Th2 secrete?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Anemias (esp due to renal failure)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
IL 4 - 5 - 10 - 6

26. What is the clinical use for sirolimus? what should you combine it with?
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Cells that stil have weird parts of their membrane that macrophages usually bite off
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)

27. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
pathogenesis
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Anti glutamate carboxylase and anti insulin

28. where do NK cells develop?
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
NK cells
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Not thymus - BM

29. which interleukin receptor is required for NK development? activation?
IL 15; IL 12 - interferon Beta and interferon alpha
Anti mitochondrial
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Graves

30. hat is the presentation of Jobs syndrome or Hyper IgE?
IL 4 - 5 - 10 - 6
opsonizes
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

31. So antibodies are the effectors for the humoral response. List some of their functions.
...
B - T - and NK cells
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

32. 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).
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
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!
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

33. What are the autoantibodies for polymyositis and dermatomyositis?
Anti Jo -1
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

34. What type of fenestrations are found in the red pulp of the spleen?
Cells that stil have weird parts of their membrane that macrophages usually bite off
Edema and necrosis in that region
Barrel hoop basement membrane fenestrations
Paracortex

35. What is the autoantibody for SLE that is nonspecific? Specific?
Thrombocytopenia
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Bind FcG for antibody dependent cellular cytotoxicity
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)

36. What is epo used for?
Previous transfusion; pregnant woman whose fetus had paternal antigens
TGF beta and IL 10
Anemias (esp due to renal failure)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

37. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
isotype
TNF alpha and IL1
...
Tetanus - Botulinum - HBV - Rabies

38. other than eat and bite RBCs what else do Macrophages of spleen do>
Active; passive - fast but short half life (3 weeks!)
Axillary
Carbohydrate
Remove encapsulated bacateria

39. 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
Secretory component
Axillary
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

40. What are the autoantibodies for wegeners granulomatosis?
MHC II - B7
active complement pathway
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
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

41. T/F B cells do not require a second signal
False! B cell class switching requires a second signal
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
Para aortic
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

42. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
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
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
MHC class molecules bind to KIRS or CD94 to prevent killing
Alternative splicing of mRNA

43. How does complement link innate and adaptive?
Axillary
Alternative splicing of mRNA
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Popliteal

44. Name 5 ways Antibody diversity is generated?
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
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
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

45. What is serum sickness? give an example.
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
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
mesenchymal

46. 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)?
Severe pyogenic infections early in life
secondary
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
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

47. Name two endogenous pyrogens
Macrophages - Dendritic cells - B cells
When you select for which MHC it will have; take out the lymphs that self react
IL 1 and IL 6
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

48. Type IV hypersensitivity is i...
heavy chains
Sinusitis - otitis media - pneumonia
not Ab mediated
CD21 on B cells (although there is T cell lymphocytosis in EBV)

49. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Axillary
...
Complement activation (active in both)
Activates Th1 helper cells; Macrophages

50. give an example of how influenza does a major antigenic shift.
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
CRP - C3b - IgM
RNA segment reassortment