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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. How fast does it occur?
The patient could become cyanotic in the OR!
Histamine; post capillary venules - vasodilation
Thrombocytopenia
opsonizes

2. Which disease is associated with HLA A3?
Hemochromatosis
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
carboxy terminal
Immunoflourescent staining of tissue biopsies

3. A lymph node is a ________ lymphoid organ.
DM type I
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
Previous transfusion; pregnant woman whose fetus had paternal antigens
secondary

4. Which disease is associated with B8?
Graves
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
A recomb cytokine of IL 2; RCC and metastatic melanoma
IL 3; supports growth and differentiation of bone marrow stem cells

5. What lymph node drains the upper limb?
Axillary
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
MS
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

6. what secretes IL 4?
False! B cell class switching requires a second signal
Basophils! THey want IG E class switch!
Interferon gamma; Th1
MHC I; from RER with help of the B2 microglobulin

7. The lymphocytes are ________ origin
Hemochromatosis
mesenchymal
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Receiving preformed Antibodies

8. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
MHC class molecules bind to KIRS or CD94 to prevent killing
TNF alpha and IL1
IgG
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. What happens when a T helper cell in the paracortical section encounters an antigen? a cytotoxic t cell? a B cell in the cortical section?
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
By transcytosis
2 heavy chains and two light chains
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

10. hat is the presentation of Jobs syndrome or Hyper IgE?
Recom IL 11; thrombocytopenia
Antidote for digoxin intoxication
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
SP infections

11. What is an example of a parasite showing antigenic variation?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
RNA segment reassortment
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
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

12. What can cause a lymph node enlargement?
Local infection/inflammation; infection of the ln itself; metastasis
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
T
Hereditary angioedema; PNH

13. What is the pathology seen in chronic transplant rejection?
Immunosuppression after kidney transplantation
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
A recomb cytokine of IL 2; RCC and metastatic melanoma
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

14. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
SP infections
Anti TSh receptor
A - B - C; all the D's
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

15. What is muromonab - CD3 (OKT3)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Lymphocytes
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
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

16. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Found in the red pulp; contains the cords of billroth or the splenic parenchyma that have APCs/Macrophages that closely interact with the basement membrane of the vasculature and where RBCs squeeze through into the parenchyma and interact with Macrop
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
TLR ad nuclear receptors

17. 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)?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Rheumatic arthritis
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
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

18. What are C1 - C2 - C3 - C4 important for?
IgG
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
By transcytosis
Viral neutralization of igM and IgG!

19. where do somatic hypermutation and class switching occur?
IL 4 - 5 - 10 - 6
Kill them because they have CD16 on them that recognize the FcG portion
cannot cross placenta
In the germinal center of secondary follicles (In the paler center)

20. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
All MHC 1/CD8
...
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
2 heavy chains and two light chains

21. The Fc region is found on the...
carboxy terminal
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Sinusitis - otitis media - pneumonia
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

22. What are the three types of APCs?
Cytokine IL 10 secreted by Th2
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
All MHC 1/CD8
Macrophages - Dendritic cells - B cells

23. What are the autoantibodies for primary biliary cirrhosis?
MHC II - B7
Stimulate the liver to release acute phase reactants
Anti mitochondrial
Fab portion

24. What are the autoantibodies for Mixed connective tissue disease?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
All MHC 1/CD8
Anti U1 RNP (ribonucleoprotein)

25. What are the labs in brutons agammaglobulinemia?
High endothelial venules are post capillary cuboidal endothelial cells that contain specific adhesion molecules for lymphocytes with specific binders that allows for lymphocytes to drain out of the vasculature into the lymph node structure (this is h
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Daclizumab; prevent ACUTE rejection of renal transplant
A j chain

26. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Anti topoisomerase
Graves
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

27. 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?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Fab portion
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
A j chain

28. What is the pathogenesis of a candida skin test?
Delayed type hypersensitivity
Increases expression of MHC I and MHC II and also activates NK cells
Graves
Viral neutralization of igM and IgG!

29. What is thrombopoietin used for?
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
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
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
Thrombocytopenia

30. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
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
Superior mesenteric
IgA
Cross link

31. What is the presentation of hyperIgM syndrome?
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
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Severe pyogenic infections early in life
Inferior mesenteric

32. What are the autoantibodies for hashimotos?
...
Carbohydrate
Superficial inguinal
Antimicrosomal and antithyroglobulin

33. The two heavy chains of an antibody contribute to the...
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Interferon gamma and IL 2
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Fab portion

34. What does it mean if there are igM in the serum at birth?
Superficial inguinal
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
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
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

35. In thymic development - What is the positive selection? negative selections?
Superficial inguinal
Anti U1 RNP (ribonucleoprotein)
When you select for which MHC it will have; take out the lymphs that self react
Interferon gamma; Th1

36. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

37. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
MHC class molecules bind to KIRS or CD94 to prevent killing
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
CD21 on B cells (although there is T cell lymphocytosis in EBV)

38. which type of immunity is slow but long lasting? as opposed to...
Active; passive - fast but short half life (3 weeks!)
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Axillary
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

39. Which is the most abundant antibody in blood?
T cell dysfunction
type four
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
IgG

40. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
neutrophilia!
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected 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
High endothelial venules are post capillary cuboidal endothelial cells that contain specific adhesion molecules for lymphocytes with specific binders that allows for lymphocytes to drain out of the vasculature into the lymph node structure (this is h

41. 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?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
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

42. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
IgE
Tetanus - Botulinum - HBV - Rabies
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

43. What are the two signals required for Th1 cells? what happens after then activated?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Anti TSh receptor
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
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

44. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Activates Th1 helper cells; Macrophages
Its a serine protease that activates apoptosis; NK and CD8
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

45. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
Negative!
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

46. can igG cross the placenta?
The igA found in breast milk
Yes
Paracortex; viral infection
IgM

47. What is the treatment of acute transplant rejection?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Cyclosporine - OKT3
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

48. What are the two signals required for B cell class switching? Which is the second signal?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
heavy chains
The igA found in breast milk
IL 5

49. which antibody activate mast cells - basophils - and eosinophils?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
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
IgE
Delayed type hypersensitivity

50. What does Interferon alpha and beta do? how?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Fab portion
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
IgE; by activating eosinophils