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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. 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?
Negative!
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 cell precursor
T cell dysfunction

2. What does Interferon alpha and beta do? how?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
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
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

3. The secondary follicles have __________; primary follicles are dense
Cells that stil have weird parts of their membrane that macrophages usually bite off
Antidesmoglein
delayed!
pale central germinal centers

4. What are the main symptoms of T cell immunodeficiencies?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
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
...
A chemotactic factor for neutrophils

5. What is hereditary angioedema? What are the C3 levels?
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
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
...
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

6. What do mature naive B lymphocytes express?
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
IgM and IgD
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils

7. What are the autoantibodies for myasthenia gravis?
heavy chains
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Anti Ach receptor
IgAs in mothers breast milk!

8. What lymph node drains the anal canal (below the pectinate line)?
Superficial inguinal
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Its main effect is a defect in Ab opsonization for killing
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation

9. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
IgG
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

10. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Secretory component
Alternative splicing of mRNA
Previous transfusion; pregnant woman whose fetus had paternal antigens

11. 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 topoisomerase
A - B - C; all the D's
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
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

12. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Humoral
Activate macrophages

13. What is the main function of IL 8?
A chemotactic factor for neutrophils
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Cells that stil have weird parts of their membrane that macrophages usually bite off
Cytokine IL 10 secreted by Th2

14. So antibodies are the effectors for the humoral response. List some of their functions.
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
TLR ad nuclear receptors

15. What is the main function of IL 12? other than macrophages who else can release IL 12?
Graves
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Daclizumab; prevent ACUTE rejection of renal transplant

16. The idiotype; the Fc portion determines the...
isotype
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
A chemotactic factor for neutrophils
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

17. What links the adaptive and innate immunity?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Superficial inguinal
Complement activation (active in both)

18. What are the autoantibodies for drug induced lupus?
Popliteal
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Antihistone
IgE; by activating eosinophils

19. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
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
Influenza; antigenic shift; antigenic drift
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

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?
False! B cell class switching requires a second signal
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
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
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

21. What are the PALS?
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
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
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

22. Which disease is associated with DR3?
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
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
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
DM type I

23. What happens in a deficiency of C3?
Increases expression of MHC I and MHC II and also activates NK cells
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
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
IL 3; supports growth and differentiation of bone marrow stem cells

24. A lymph node is a ________ lymphoid organ.
Thrombocytopenia
secondary
Hemochromatosis
IgG

25. What are the symptoms of serum sickness?
Immunoflourescent staining of tissue biopsies
Pernicious Anemia and Hashimotos
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Antihistone

26. What is the pathogenesis of acute transplant rejection? When does it occur?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
heavy chains
Axillary
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

27. Which disease is associated withB B27?
C5a
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
pentamer
MS - hay fever - SLE - goodpastures

28. What does granzyme do? who secretes it?
Fab portion
The igA found in breast milk
Interferon gamma and IL 2
Its a serine protease that activates apoptosis; NK and CD8

29. what bacteria are a splenectomy patient most susceptible to? why?
Anti U1 RNP (ribonucleoprotein)
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
pale central germinal centers
Sinusitis - otitis media - pneumonia

30. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
...
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
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
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

31. 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
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
Superficial inguinal
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

32. give an example of how influenza does a major antigenic shift.
Immunosuppression after kidney transplantation
not Ab mediated
RNA segment reassortment
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

33. what happens in a deficiency of C1 esterase inhibitor? DAF?
If there is class switching and plasma cell production (that is when memory cells are produced)
Hereditary angioedema; PNH
except hyperacute
Humoral

34. What are the autoantibodies for graves?
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 :(
Anti TSh receptor
2 heavy chains and two light chains
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)

35. What does interferon gamma do? What two type of cells does it attack mostly?
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!
cannot cross placenta
S. aureus - E. Coli - aspergillus
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

36. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
All MHC 1/CD8
Steroid responsive nephrotic syndrome
Receiving preformed Antibodies
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

37. Which cytokines do Th2 release and For what?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Kill them because they have CD16 on them that recognize the FcG portion
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

38. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
active complement pathway
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
MHC II - B7

39. IgE has the ___________ in the serum
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
lowest concentration
Antihistone
Fab portion

40. is IgM an opsonizer?
heavy chains
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Negative!
Anti IF

41. are Th cells involved in trapping of antigens of endotoxin/LPS?
Antimicrosomal and antithyroglobulin
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
No because no peptide fragment!

42. What is the main cytokine released by T cells? What does it do
Not thymus - BM
IL 3; supports growth and differentiation of bone marrow stem cells
Hereditary angioedema; PNH
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

43. ________ regulate the cell mediated response.
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Activates Th1 helper cells; Macrophages
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
Humoral

44. What cytokines are released by Th1 cells?
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
Interferon gamma and IL 2
Anti Jo -1
Thrombocytopenia

45. What can cause a lymph node enlargement?
heavy chains
Local infection/inflammation; infection of the ln itself; metastasis
carboxy terminal
Daclizumab; prevent ACUTE rejection of renal transplant

46. The ______ in the BM are DN - the DP are in the cortex of thymus
Anti mitochondrial
T cell precursor
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
TGF beta and IL 10

47. Which antibodies can be multimeric?
...
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
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
IgM and IgA

48. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Anti U1 RNP (ribonucleoprotein)
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
Rheumatic arthritis
Sinusitis - otitis media - pneumonia

49. Which disease is associated with DR7?
Steroid responsive nephrotic syndrome
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
opsonizes
Activates cytotoxic CD 8 T cells as second signal

50. What lymph node drains the stomach?
type four
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Celiac