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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 the three types of lymphocytes?
Fab portion
B - T - and NK cells
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
encapsulated

2. What is the pathology of acute transplant rejection? is it reversible?
MHC I; from RER with help of the B2 microglobulin
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
Anti mitochondrial
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

3. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Alternative splicing of mRNA
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

4. What lymph node drains the stomach?
Celiac
B - T - and NK cells
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)
Inferior mesenteric

5. which antibodies can bind complement?
IgM and IgG
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
Delayed type hypersensitivity
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

6. What are the main cell surface proteins on B cells?
Antidesmoglein
Superficial inguinal
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Activate macrophages

7. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Active; passive - fast but short half life (3 weeks!)
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IL 3; supports growth and differentiation of bone marrow stem cells

8. What is the most common example of passive immunity?
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
IgAs in mothers breast milk!
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

9. what cell surface marker is used for NK cells as it is unique to them?
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
CD56
Negative!
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

10. What are the autoantibodies for goodpastures syndrome?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Anti alpha subunit 3 of collagen on type IV bm
Anti topoisomerase
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

11. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
CRP - C3b - IgM
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

12. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Activate macrophages
Th2; Th1
lowest concentration
Anti glutamate carboxylase and anti insulin

13. What are the autoantibodies for systemic sclerosis?
encapsulated
Anti topoisomerase
RNA segment reassortment
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

14. What is recomb alpha interferon used for?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
secondary
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

15. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
IL 4
IL 15; IL 12 - interferon Beta and interferon alpha

16. What is the clinical use for azathioprine?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
IgM and IgA
...
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

17. __________ are a part of the innate system.
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
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
NK cells
IgA

18. What is the pathology seen in chronic transplant rejection?
Interferon gamma and IL 2
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
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
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

19. What are the main symptoms of B cell immunodeficiencies?
SP infections
Internal iliac
Graves
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

20. What happens in a secondary follicle?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Hereditary angioedema; PNH
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Wiskott Aldrich syndrome

21. What is an example of a parasite showing antigenic variation?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Anti IF
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Cytokine IL 10 secreted by Th2

22. What lymph node drains the thigh?
MHC class molecules bind to KIRS or CD94 to prevent killing
Chronic granulomatous disease
Superficial inguinal
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

23. what characterizes an arthus reaction?
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
Antidesmoglein
Edema and necrosis in that region
Secretory component

24. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Anti Jo -1
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
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!

25. 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?
The igA found in breast milk
IgE; by activating eosinophils
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
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

26. What lymph node drains the upper limb?
Axillary
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
Anti viral and anti tumor
MS

27. what ensure that a memory response is generated?
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
Carbohydrate
If there is class switching and plasma cell production (that is when memory cells are produced)
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

28. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Celiac
Interferon gamma; Th1
Histamine; post capillary venules - vasodilation

29. IgM can fix complement but...
cannot cross placenta
Secretory component
carboxy terminal
Liver! (they are proteins circulating in the blood)

30. What is the general structure of an Ab?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
2 heavy chains and two light chains
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

31. What does IL 10 do? who is secreted by?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
isotype

32. What is passive immunity?
Anti IF
Cells that stil have weird parts of their membrane that macrophages usually bite off
Receiving preformed Antibodies
IL 1 and IL 6

33. What are C1 - C2 - C3 - C4 important for?
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Viral neutralization of igM and IgG!
T cell activation; no with CD 4 or CD 8
DM type I

34. How does igA cross the epithelium?
By transcytosis
Negative selection
In the germinal center of secondary follicles (In the paler center)
Delayed type hypersensitivity

35. What are the autoantibodies for primary biliary cirrhosis?
IgAs in mothers breast milk!
Anti mitochondrial
secondary
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

36. other than eat and bite RBCs what else do Macrophages of spleen do>
Remove encapsulated bacateria
Recom IL 11; thrombocytopenia
Anti alpha subunit 3 of collagen on type IV bm
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

37. What is the main function of IL 12? other than macrophages who else can release IL 12?
Activates Th1 helper cells; Macrophages
Anti SS- A (anti RO) and Anti SS- B
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
B - T - and NK cells

38. What are the major functions of Antibodies?
active complement pathway
Histamine; post capillary venules - vasodilation
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Negative selection

39. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
encapsulated
Glycoproteins; HLA
T cell activation; no with CD 4 or CD 8
Sinusitis - otitis media - pneumonia

40. What are the labs in brutons agammaglobulinemia?
If there is class switching and plasma cell production (that is when memory cells are produced)
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
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 :(

41. A lymph node is a ________ lymphoid organ.
IgM and IgG
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
secondary
IL 3; supports growth and differentiation of bone marrow stem cells

42. What are the autoantibodies for sjorgens syndrome?
carboxy terminal
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Anti SS- A (anti RO) and Anti SS- B
Superficial inguinal

43. What is the receptor for EBV? On what cells is that located?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Its main effect is a defect in Ab opsonization for killing

44. What do multimeric antibodies require for assembly?
Basophils! THey want IG E class switch!
Anti U1 RNP (ribonucleoprotein)
A j chain
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!

45. What does CD16 on NK cells do?
DM type I and RA
Bind FcG for antibody dependent cellular cytotoxicity
A - B - C; all the D's
Graves

46. What is the main function of IL 8?
Histamine; post capillary venules - vasodilation
IgM and IgA
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
A chemotactic factor for neutrophils

47. What lymph node drains the testes?
Para aortic
A chemotactic factor for neutrophils
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
DM type I and RA

48. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
Paracortex; viral infection
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
pentamer

49. What does IL 5 do?
Sinusitis - otitis media - pneumonia
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
heavy chains

50. Describe the complement independent Type II hypersenstivity reaction. Give an example.
TNF alpha and IL1
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
pentamer