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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. From where do cytokines come from?
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
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Lymphocytes
IL 4 - 5 - 10 - 6

2. What are the main symptoms of B cell immunodeficiencies?
When you select for which MHC it will have; take out the lymphs that self react
SP infections
The patient could become cyanotic in the OR!
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

3. which antibody activate mast cells - basophils - and eosinophils?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Activates cytotoxic CD 8 T cells as second signal
IgE
If there is class switching and plasma cell production (that is when memory cells are produced)

4. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
T cell activation; no with CD 4 or CD 8
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
MS - hay fever - SLE - goodpastures

5. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
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
Hemochromatosis
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
MS - hay fever - SLE - goodpastures

6. What are the autoantibodies for Celiac disease?
IgAs in mothers breast milk!
Anti U1 RNP (ribonucleoprotein)
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Bind FcG for antibody dependent cellular cytotoxicity

7. What is the pathology in hyperacute transplant rejection?
Lymphocytes
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
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

8. What is chronic mucocutaneous candidiasis d/t?
Antibody mediated cytotoxicity; either complement dependent or complement independent
Sinusitis - otitis media - pneumonia
Daclizumab; prevent ACUTE rejection of renal transplant
T cell dysfunction

9. The pathogenesis of contact dermatitis is ________ hypersensitivity
type four
Carbohydrate
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Pernicious Anemia and Hashimotos

10. What are the T cell functions?
Cross link
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
IL 15; IL 12 - interferon Beta and interferon alpha

11. where do NK cells develop?
Para aortic
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
IgM
Not thymus - BM

12. What is filgrastim and sargramostim? and What is it used for?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
IgE; by activating eosinophils
IgM and IgG
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

13. What do mature naive B lymphocytes express?
Antidesmoglein
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Steroid responsive nephrotic syndrome
IgM and IgD

14. Describe the complement independent Type II hypersenstivity reaction. Give an example.
...
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

15. What is the receptor for EBV? On what cells is that located?
secondary
Anti Ach receptor
CD21 on B cells (although there is T cell lymphocytosis in EBV)
B - T - and NK cells

16. How do you test for chronic granulomatous disease?
Its a serine protease that activates apoptosis; NK and CD8
Negative nitroblue tetrazolium reduction test
Antidote for digoxin intoxication
Type IV

17. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
Paracortex; viral infection
Histamine; post capillary venules - vasodilation
Inferior mesenteric
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

18. What is muromonab - CD3 (OKT3)
Recom IL 11; thrombocytopenia
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
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
Severe pyogenic infections early in life

19. what cytokine does basophils secrete?
IL 4
Anti Ach receptor
The patient could become cyanotic in the OR!
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

20. What does IL 5 do?
T cell dysfunction
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
MS - hay fever - SLE - goodpastures

21. other than C3a - what other complement acts as an anaphyloxin?
heavy chains
C5a
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
RNA segment reassortment

22. What is anergy? why does this occur?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids

23. What lymph node drains the anal canal (below the pectinate line)?
B - T - and NK cells
Hereditary angioedema; PNH
Humoral
Superficial inguinal

24. What is the pathology of acute transplant rejection? is it reversible?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Cyclosporine - OKT3
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

25. Name 5 ways Antibody diversity is generated?
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Antihistone
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids

26. What is an example of a parasite showing antigenic variation?
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 :(
Acts as second signal on B cells to induce class switching to IgE and IgG
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

27. What are the function of B cells?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
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

28. What is the pathogenesis of a candida skin test?
Delayed type hypersensitivity
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Anemias (esp due to renal failure)
Pernicious Anemia and Hashimotos

29. What are the autoantibodies for drug induced lupus?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Complement activation (active in both)
Antihistone

30. What is the main function of interferons?
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
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
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Interferon gamma and IL 2

31. The ______ in the BM are DN - the DP are in the cortex of thymus
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
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
T cell precursor
Activate macrophages

32. Which disease is associated withB B27?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Axillary
MHC II - B7
Cytokine IL 10 secreted by Th2

33. Give three examples of bacteria that use antigenic variation and how.
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
lowest concentration
C5a
Anti U1 RNP (ribonucleoprotein)

34. What is hereditary angioedema? What are the C3 levels?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Anti smooth muscle
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

35. A lymph node is a ________ lymphoid organ.
Immunoflourescent staining of tissue biopsies
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
secondary
Anti SS- A (anti RO) and Anti SS- B

36. Describe the capsular structure of a lymph node; What are the functions of the LN?
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
T cell activation; no with CD 4 or CD 8
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
Acts as second signal on B cells to induce class switching to IgE and IgG

37. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
DM type I and RA
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
IgE; by activating eosinophils
Celiac

38. What are target cells?
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
...
Anti Jo -1
Cells that stil have weird parts of their membrane that macrophages usually bite off

39. What is the defect in hyper IgM syndrome? What are the lab results?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Alternative splicing of mRNA
Anti SS- A (anti RO) and Anti SS- B

40. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Interferon gamma and IL 2
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Antidote for digoxin intoxication

41. The idiotype; the Fc portion determines the...
Remove encapsulated bacateria
Basophils! THey want IG E class switch!
isotype
Para aortic

42. What is the most common example of passive immunity?
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
IgAs in mothers breast milk!

43. What does interferon gamma do to be antiviral?
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
Th cells fail to produce interferon gamma; a lot of IgE
Increases expression of MHC I and MHC II and also activates NK cells
IgE

44. What does CD16 on NK cells do?
Severe pyogenic infections early in life
Bind FcG for antibody dependent cellular cytotoxicity
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

45. What is the mechanism for sirolimus? what else it known as?
Wiskott Aldrich syndrome
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
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
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

46. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Th2; Th1
Activates Th1 helper cells; Macrophages
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

47. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
pathogenesis
Antimicrosomal and antithyroglobulin
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

48. What is the main function of IL 8?
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
MHC class molecules bind to KIRS or CD94 to prevent killing
A chemotactic factor for neutrophils
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

49. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
lowest concentration
CRP - C3b - IgM
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
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

50. What are the autoantibodies for Mixed connective tissue disease?
Sinusitis - otitis media - pneumonia
Anti U1 RNP (ribonucleoprotein)
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
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)