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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. Which is the main antibody that provides passive immunity to infants?
IgG
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Anti TSh receptor
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

2. Leukocyte adhesion defect presents with...
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
IL 4 - 5 - 10 - 6
neutrophilia!
IgM and IgD

3. which antibodies can bind complement?
IgA
Celiac
IgM and IgG
MHC I - CD16 - CD56

4. which cells have more complete tolerance - B or T cells?
T
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
IL 1 and IL 6
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

5. The lymphocytes are ________ origin
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
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
mesenchymal
C5a

6. Give an example of someone who could get hyperacute transplant rejection.
MS
Previous transfusion; pregnant woman whose fetus had paternal antigens
2 heavy chains and two light chains
Delayed type hypersensitivity

7. Name two endogenous pyrogens
IL 1 and IL 6
MHC class molecules bind to KIRS or CD94 to prevent killing
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

8. what bacteria are a splenectomy patient most susceptible to? why?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
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
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
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

9. How does complement link innate and adaptive?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
False! B cell class switching requires a second signal
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

10. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Activate macrophages
DM type I and RA
NK cells

11. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
TLR ad nuclear receptors
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

12. 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
TNF alpha and IL1
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

13. what cell surface marker is used for NK cells as it is unique to them?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
CD56
IgM and IgG
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

14. What are the autoantibodies for goodpastures syndrome?
Anti alpha subunit 3 of collagen on type IV bm
Antibody mediated cytotoxicity; either complement dependent or complement independent
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Chronic granulomatous disease

15. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Activates Th1 helper cells; Macrophages
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
CD21 on B cells (although there is T cell lymphocytosis in EBV)

16. What type of side chains are found on Fc region of an antibody?
Carbohydrate
False! B cell class switching requires a second signal
IL 3; supports growth and differentiation of bone marrow stem cells
Superficial inguinal

17. which cytokine inhibits TH2 cells? secreted by who?
Interferon gamma; Th1
CD56
Local infection/inflammation; infection of the ln itself; metastasis
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

18. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Glycoproteins; HLA
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
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
All MHC 1/CD8

19. What is serum sickness? give an example.
Fc
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
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

20. what cell surface proteins are on all APCs?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
MHC II - B7
TGF beta and IL 10
Barrel hoop basement membrane fenestrations

21. What does granzyme do? who secretes it?
IgM and IgG
IgG
Antimicrosomal and antithyroglobulin
Its a serine protease that activates apoptosis; NK and CD8

22. What are the two signals required for Th1 cells? what happens after then activated?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
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
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

23. What part of the lymph node specifically expands during a cellular immune response? when would this occur?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
heavy chains
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Paracortex; viral infection

24. what secretes IL 4?
Hereditary angioedema; PNH
IL 4 - 5 - 10 - 6
Antidesmoglein
Basophils! THey want IG E class switch!

25. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
MHC I - CD16 - CD56
For some reason a mature naive B lymphocyte got away from tolerance and the result was a production an Ab on its surface with an Fab region that recognized the alpha 3 collagen subunit on the BM as non self. It then gets activated by a Th2 cell (enti
opsonizes
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. How does the alternative pathway lead to MAC activation?
MHC I; from RER with help of the B2 microglobulin
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
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
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

27. What is the clinical use for sirolimus? what should you combine it with?
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
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
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
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

28. How is sirolimus different from tacrolimus?
Celiac
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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
Steroid responsive nephrotic syndrome

29. which of the hypersensitivity reactions is not Ab mediated?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Type IV
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

30. The MALT/GALT are not...
TNF alpha and IL1
encapsulated
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
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!

31. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
type four
Rheumatic arthritis
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)

32. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Antimicrosomal and antithyroglobulin
Anti Ach receptor
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

33. What are the autoantibodies for sjorgens syndrome?
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
Paracortex; viral infection
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
Anti SS- A (anti RO) and Anti SS- B

34. What are the autoantibodies for pemphigus bulgaris?
Anti U1 RNP (ribonucleoprotein)
Th cells fail to produce interferon gamma; a lot of IgE
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
Antidesmoglein

35. What is digoxin immune Fab used for?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
carboxy terminal
Antidote for digoxin intoxication

36. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
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
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
Influenza; antigenic shift; antigenic drift
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

37. The pathogenesis of contact dermatitis is ________ hypersensitivity
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
type four
Anti IF
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

38. What lymph node drains the sigmoid colon?
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
Inferior mesenteric
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

39. What is the main function of IL 12? other than macrophages who else can release IL 12?
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Its a serine protease that activates apoptosis; NK and CD8
Delayed type hypersensitivity

40. What does interferon gamma do to be antiviral?
Negative selection
MHC class molecules bind to KIRS or CD94 to prevent killing
Increases expression of MHC I and MHC II and also activates NK cells
A recomb cytokine of IL 2; RCC and metastatic melanoma

41. What kinds of receptors activate innate immunity?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
TLR ad nuclear receptors
Kill them because they have CD16 on them that recognize the FcG portion
pale central germinal centers

42. What are the autoantibodies for pernicious anemia?
acute phase reactants
Anti IF
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

43. How is i Th1 helper cell inhibited?
IgG
The patient could become cyanotic in the OR!
Anti smooth muscle
Cytokine IL 10 secreted by Th2

44. How is the antigen loaded onto a MHC II?
Yes
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
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

45. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Histamine; post capillary venules - vasodilation
Paracortex; viral infection
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Immunoflourescent staining of tissue biopsies

46. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
opsonizes
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

47. What do multimeric antibodies require for assembly?
Stimulate the liver to release acute phase reactants
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
A j chain
Rheumatic arthritis

48. where do somatic hypermutation and class switching occur?
Histamine; post capillary venules - vasodilation
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
C5a
In the germinal center of secondary follicles (In the paler center)

49. In general What are T cells good for?
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
NK cells
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Anti viral and anti tumor

50. What lymph node drains the lateral side of the dorsum of the foot?
Axillary
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Popliteal
Anti Jo -1