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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
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 happens in a deficiency of C3?
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
Histamine; post capillary venules - vasodilation
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

2. What does interferon gamma do? What two type of cells does it attack mostly?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
neutrophilia!

3. What is the clinical use for azathioprine?
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
...
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
T cell activation; no with CD 4 or CD 8

4. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
neutrophilia!
Influenza; antigenic shift; antigenic drift
Pernicious Anemia and Hashimotos
Receiving preformed Antibodies

5. What lymph node drains the upper limb?
Axillary
Alternative splicing of mRNA
Anti smooth muscle
Interferon gamma and IL 2

6. What is recomb alpha interferon used for?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Delayed type hypersensitivity
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

7. T/F B cells do not require a second signal
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
False! B cell class switching requires a second signal
Anemias (esp due to renal failure)
TNF alpha and IL1

8. What is the late phase reaction of anaphylaxis allergy? what mediates it?
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 :(
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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)
opsonizes

9. which interleukin receptor is required for NK development? activation?
Antidesmoglein
IL 15; IL 12 - interferon Beta and interferon alpha
Its a serine protease that activates apoptosis; NK and CD8
cannot cross placenta

10. What lymph node drains the testes?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
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
Para aortic
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

11. The idiotype; the Fc portion determines the...
type four
Anti Ach receptor
MHC I; from RER with help of the B2 microglobulin
isotype

12. What is the general structure of an Ab?
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
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
TLR ad nuclear receptors
2 heavy chains and two light chains

13. What are the main symptoms of T cell immunodeficiencies?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Antibody mediated cytotoxicity; either complement dependent or complement independent

14. IgM can exist as a _______ also
pentamer
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Interferon gamma and IL 2
pale central germinal centers

15. which of the transplant rejections is antibody mediated? why does it occur?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Alternative splicing of mRNA
No because no peptide fragment!

16. Which MHC presents intracellular peptides? how so?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
MHC I; from RER with help of the B2 microglobulin
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

17. What is the most common example of passive immunity?
isotype
IgAs in mothers breast milk!
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Anti topoisomerase

18. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
The patient could become cyanotic in the OR!
Hereditary angioedema; PNH
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

19. In thymic development - What is the positive selection? negative selections?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
When you select for which MHC it will have; take out the lymphs that self react
Cells that stil have weird parts of their membrane that macrophages usually bite off

20. What is oprelevkin? and What is it used for?
Interferon gamma; Th1
Increases expression of MHC I and MHC II and also activates NK cells
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Recom IL 11; thrombocytopenia

21. What is the common variable immunodeficiency ? How is it different from Brutons?
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
Antibody mediated cytotoxicity; either complement dependent or complement independent
DM type I and RA

22. give an example of how influenza does a major antigenic shift.
RNA segment reassortment
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
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
Cross link

23. What are the cell surface proteins for Macrophages? which two are for opsonins?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Fab portion
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Anti viral and anti tumor

24. What are the main cell surface proteins on B cells?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Paracortex; viral infection
Alternative splicing of mRNA
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

25. The lymphocytes are ________ origin
mesenchymal
MS
Receiving preformed Antibodies
TGF beta and IL 10

26. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
If there is class switching and plasma cell production (that is when memory cells are produced)
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Glycoproteins; HLA
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after

27. What is the white pulp of the spleen?
A recomb cytokine of IL 2; RCC and metastatic melanoma
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
S. aureus - E. Coli - aspergillus
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

28. To what disease do the autoantibodies to IgG (rheumatoid factor)?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
...
Anti mitochondrial
Rheumatic arthritis

29. How is i Th1 helper cell inhibited?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
secondary
Cytokine IL 10 secreted by Th2
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

30. How is the antigen loaded onto a MHC II?
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
Stimulate the liver to release acute phase reactants
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Paracortex

31. What is the main function of TNF alpha? How does it do this?
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
Superficial inguinal
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Sinusitis - otitis media - pneumonia

32. What type of fenestrations are found in the red pulp of the spleen?
Barrel hoop basement membrane fenestrations
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
Remove encapsulated bacateria
A recomb cytokine of IL 2; RCC and metastatic melanoma

33. What is the marginal zone of the spleen? what happens there?
S. aureus - E. Coli - aspergillus
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
MHC II - B7
TGF beta and IL 10

34. What is the pathology seen in chronic transplant rejection?
Antimicrosomal and antithyroglobulin
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
Negative nitroblue tetrazolium reduction test
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

35. describe the classic complement pathway.
DM type I
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
DM type I and RA

36. What is immune complex disease? give an example.
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
A chemotactic factor for neutrophils
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Cytokine IL 10 secreted by Th2

37. How does the alternative pathway lead to MAC activation?
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
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Th2; Th1
Cyclosporine - OKT3

38. what cell surface marker is used for NK cells as it is unique to them?
IgG
CD56
Glycoproteins; HLA
Superficial inguinal

39. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
T
Influenza; antigenic shift; antigenic drift

40. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Type IV
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
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

41. in which immunodef order do you see a lot of pus? no pus?
Th cells fail to produce interferon gamma; a lot of IgE
Anti viral and anti tumor
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
T cell dysfunction

42. What do multimeric antibodies require for assembly?
2 heavy chains and two light chains
A j chain
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

43. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
Previous transfusion; pregnant woman whose fetus had paternal antigens
not Ab mediated
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

44. IgE has the ___________ in the serum
Anti Ach receptor
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
lowest concentration
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

45. __________ are a part of the innate system.
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
NK cells
not Ab mediated
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

46. Name two endogenous pyrogens
Anti alpha subunit 3 of collagen on type IV bm
IL 4
dimer
IL 1 and IL 6

47. Which diseases are associated with DR2?
Superficial inguinal
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
MS - hay fever - SLE - goodpastures
IgG

48. what will NK cells do to cells covered in IgG Ab? why?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Kill them because they have CD16 on them that recognize the FcG portion
...

49. What are the autoantibodies for myasthenia gravis?
Sinusitis - otitis media - pneumonia
2 heavy chains and two light chains
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Anti Ach receptor

50. What is the clinical use of Muromonab?
Daclizumab; prevent ACUTE rejection of renal transplant
Immunosuppression after kidney transplantation
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
Internal iliac