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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. which of the hypersensitivity reactions is not Ab mediated?
neutrophilia!
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Type IV
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

2. What is the autoantibody for SLE that is nonspecific? Specific?
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
IgA
IgM
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

3. what ensure that a memory response is generated?
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
If there is class switching and plasma cell production (that is when memory cells are produced)
All MHC 1/CD8

4. What does IL 4 do?
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!
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
IgE; by activating eosinophils
Acts as second signal on B cells to induce class switching to IgE and IgG

5. The idiotype; the Fc portion determines the...
Para aortic
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Paracortex; viral infection
isotype

6. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Anti Ach receptor
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Severe pyogenic infections early in life
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

7. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
Recom IL 11; thrombocytopenia
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
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Alternative splicing of mRNA

8. What does IL 10 do? who is secreted by?
Cross link
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Anti U1 RNP (ribonucleoprotein)
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

9. IgM can exist as a _______ also
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Superficial inguinal
pentamer

10. How is sirolimus different from tacrolimus?
Anti U1 RNP (ribonucleoprotein)
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
lowest concentration
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

11. What type of fenestrations are found in the red pulp of the spleen?
Barrel hoop basement membrane fenestrations
type four
Its a serine protease that activates apoptosis; NK and CD8
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

12. can igG cross the placenta?
Yes
Anti viral and anti tumor
Pernicious Anemia and Hashimotos
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

13. What kinds of receptors activate innate immunity?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Anti topoisomerase
TLR ad nuclear receptors
carboxy terminal

14. What is the pathology of acute transplant rejection? is it reversible?
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
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Anti mitochondrial
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

15. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
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
Fab portion
IL 4

16. 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
Its a serine protease that activates apoptosis; NK and CD8
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
C5a

17. Which type of selection of thymic development provides central tolerance?
Negative selection
carboxy terminal
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

18. What is the difference of IgE AIHA and IgG AIHA if they are both complement dependent type II hypersensitivities?
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
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
IgE; by activating eosinophils
Humoral

19. What is the presentation of scid? treatment?
CD56
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
IgG

20. Monomer in circulation - ___ when secreted
IL 3; supports growth and differentiation of bone marrow stem cells
Hereditary angioedema; PNH
dimer
All MHC 1/CD8

21. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
IgAs in mothers breast milk!
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
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 :(

22. What cytokines are released by Th1 cells?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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
RNA segment reassortment
Interferon gamma and IL 2

23. What is the presentation of Brutons agammaglobulinemia?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Anti topoisomerase

24. What do multimeric antibodies require for assembly?
A j chain
Yes
Interferon gamma; Th1
Secretory component

25. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
IgG
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
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Internal iliac

26. What are superantigens? give two examples.
except hyperacute
Pernicious Anemia and Hashimotos
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
Complement activation (active in both)

27. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
pentamer
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
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
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

28. What lymph node drains the breast?
Not thymus - BM
Axillary
opsonizes
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

29. which antibodies prevent antigens from binding mucosal surfaces?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IL 15; IL 12 - interferon Beta and interferon alpha
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
IgA

30. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
By transcytosis
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Paracortex

31. What is the toxicity of muromonab?
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
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
MS - hay fever - SLE - goodpastures
Recom IL 11; thrombocytopenia

32. The Fc region is found on the...
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
carboxy terminal
Complement activation (active in both)
Recom IL 11; thrombocytopenia

33. Describe the complement independent Type II hypersenstivity reaction. Give an example.
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Fab portion
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
opsonizes

34. Name 5 ways Antibody diversity is generated?
isotype
CD56
Axillary
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

35. what will NK cells do to cells covered in IgG Ab? why?
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
Anti Jo -1
Kill them because they have CD16 on them that recognize the FcG portion
B - T - and NK cells

36. What lymph node drains the sigmoid colon?
Inferior mesenteric
Th cells fail to produce interferon gamma; a lot of IgE
Viral neutralization of igM and IgG!
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

37. What are the PALS?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

38. What lymph node drains the thigh?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
CD56
Superficial inguinal

39. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
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
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
IgE
Superior mesenteric

40. What are the autoantibodies for graves?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
S. aureus - E. Coli - aspergillus
Negative selection
Anti TSh receptor

41. other than mediating shock - what else does TNF alpha do? who releases it mainly?
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
IL 5
Activates Th1 helper cells; Macrophages
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

42. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Antidote for digoxin intoxication
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Its main effect is a defect in Ab opsonization for killing
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

43. What is the pathogenesis of acute transplant rejection? When does it occur?
IgG
Anti Jo -1
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Cytokine IL 10 secreted by Th2

44. What is recomb beta interferon used for?
No because no peptide fragment!
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
MS
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

45. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Anti IF
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

46. Leukocyte adhesion defect presents with...
A - B - C; all the D's
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
TNF alpha and IL1
neutrophilia!

47. What are the three types of APCs?
Rheumatic arthritis
Macrophages - Dendritic cells - B cells
Superficial inguinal
MHC class molecules bind to KIRS or CD94 to prevent killing

48. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
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
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

49. What is the receptor for EBV? On what cells is that located?
Hemochromatosis
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
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Previous transfusion; pregnant woman whose fetus had paternal antigens

50. What are the three types of Type III hypersensitivity ? What is the common mechanism between them?
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!