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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 does granzyme do? who secretes it?
Antimicrosomal and antithyroglobulin
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Its a serine protease that activates apoptosis; NK and CD8
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

2. What are the autoantibodies for graves?
Anti TSh receptor
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Anti mitochondrial

3. 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).
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!
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

4. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
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
2 heavy chains and two light chains
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

5. where do somatic hypermutation and class switching occur?
In the germinal center of secondary follicles (In the paler center)
IgM
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Antihistone

6. What is the clinical use of Muromonab?
Immunosuppression after kidney transplantation
IgM and IgD
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)

7. what cell surface proteins are on all APCs?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Antibody mediated cytotoxicity; either complement dependent or complement independent
IgM
MHC II - B7

8. What is the main function of interferons?
Anti alpha subunit 3 of collagen on type IV bm
Its main effect is a defect in Ab opsonization for killing
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
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 are the autoantibodies for autoimmune hepatitis?
RNA segment reassortment
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Anti smooth muscle
Superior mesenteric

10. What lymph node drains the scrotum?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Superficial inguinal
cannot cross placenta
Immunosuppression after kidney transplantation

11. What are the T cell functions?
Popliteal
A chemotactic factor for neutrophils
The igA found in breast milk
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

12. which cells have more complete tolerance - B or T cells?
T
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
TLR ad nuclear receptors
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

13. What are the autoantibodies for Celiac disease?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Activate macrophages
Paracortex

14. which interleukin receptor is required for NK development? activation?
Local infection/inflammation; infection of the ln itself; metastasis
Anti TSh receptor
IL 15; IL 12 - interferon Beta and interferon alpha
Rheumatic arthritis

15. What is the pathology of acute transplant rejection? is it reversible?
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
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
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

16. What does IL 10 do? who is secreted by?
A chemotactic factor for neutrophils
Carbohydrate
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

17. what will NK cells do to cells covered in IgG Ab? why?
carboxy terminal
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Kill them because they have CD16 on them that recognize the FcG portion
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

18. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Viral neutralization of igM and IgG!
...
Its main effect is a defect in Ab opsonization for killing
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

19. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
CD56
Histamine; post capillary venules - vasodilation
Alternative splicing of mRNA
Increases expression of MHC I and MHC II and also activates NK cells

20. Describe the Mannose Lectin pathway
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
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
...
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

21. What are the autoantibodies for primary biliary cirrhosis?
Anti mitochondrial
Antimicrosomal and antithyroglobulin
mesenchymal
IgG

22. describe the classic complement pathway.
acute phase reactants
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
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

23. which B and T cell disorder presents with specifically low IgM?
Wiskott Aldrich syndrome
IL 15; IL 12 - interferon Beta and interferon alpha
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
RNA segment reassortment

24. other than C3a - what other complement acts as an anaphyloxin?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
C5a
Anti topoisomerase
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

25. What are the labs in brutons agammaglobulinemia?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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
CRP - C3b - IgM
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

26. So antibodies are the effectors for the humoral response. List some of their functions.
Type IV
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
IgE
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

27. Which diseases are associated with DR2?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Capsule of lymph node is made up of type III collagen (made by reticulin fibers!) - extension of this collagen extends into the splenic tissue as trabeculae; nonspecific filtration of lymph by Macrophages - Antibody production (via activation) - stor
MS - hay fever - SLE - goodpastures

28. which antibody is involved in the primary response or immediate response to an antigen?
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
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
IgM
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

29. Describe complement dependent Type II hypersensitivity. Give an example.
Cytokine IL 10 secreted by Th2
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
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
IgM and IgA

30. What is Aldesleukin? What is it used for
A recomb cytokine of IL 2; RCC and metastatic melanoma
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Para aortic
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

31. What happens in a deficiency of C3?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Anti Jo -1

32. What do multimeric antibodies require for assembly?
Inferior mesenteric
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
A j chain
T cell activation; no with CD 4 or CD 8

33. 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?
MHC I - CD16 - CD56
IgE
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
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

34. What are howell jolly bodies?
Viral neutralization of igM and IgG!
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Carbohydrate

35. What lymph node drains the sigmoid colon?
IL 15; IL 12 - interferon Beta and interferon alpha
The patient could become cyanotic in the OR!
Inferior mesenteric
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

36. What does IL 2 do?
Activate macrophages
Activates cytotoxic CD 8 T cells as second signal
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
Celiac

37. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
S. aureus - E. Coli - aspergillus
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
not Ab mediated

38. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
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
encapsulated
Secretory component
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

39. What is colostrum?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
IgM and IgA
The igA found in breast milk
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

40. Which disease is associated with DR7?
DM type I and RA
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
Steroid responsive nephrotic syndrome
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

41. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Superficial inguinal
B - T - and NK cells
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

42. What are the symptoms of serum sickness?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Fab portion
Superior mesenteric

43. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Recom IL 11; thrombocytopenia
pentamer
IL 4

44. What are C1 - C2 - C3 - C4 important for?
The patient could become cyanotic in the OR!
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
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
Viral neutralization of igM and IgG!

45. Type Iv hypersensitivity is...
IgG
Antidote for digoxin intoxication
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
delayed!

46. What is recomb gamma interferon used for?
Chronic granulomatous disease
T cell dysfunction
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

47. The two heavy chains of an antibody contribute to the...
Fab portion
Into cortex and medulla; cortex is where immature T lymphocytes enter - at the corticomedullar junction is where positive and negative selection occur; and at the medulla is where the mature T lymphs - reticulin cells and hassalls corpuscles are (dea
SP infections
Paracortex

48. What are target cells?
Anti U1 RNP (ribonucleoprotein)
Superficial inguinal
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Cells that stil have weird parts of their membrane that macrophages usually bite off

49. What are the main cell surface proteins on B cells?
Anti Jo -1
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
IgG
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

50. In thymic development - What is the positive selection? negative selections?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IgM and IgA
When you select for which MHC it will have; take out the lymphs that self react
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith