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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 is i Th1 helper cell inhibited?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Cytokine IL 10 secreted by Th2
Severe pyogenic infections early in life
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma

2. What does interferon gamma do? What two type of cells does it attack mostly?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Alternative splicing of mRNA

3. 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
Anti smooth muscle
Activates Th1 helper cells; Macrophages
T cell activation; no with CD 4 or CD 8

4. What lymph node drains the lateral side of the dorsum of the foot?
Antimicrosomal and antithyroglobulin
Paracortex
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Popliteal

5. What are the labs in brutons agammaglobulinemia?
T
active complement pathway
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Steroid responsive nephrotic syndrome

6. What does granzyme do? who secretes it?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
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
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Its a serine protease that activates apoptosis; NK and CD8

7. 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?
Antihistone
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
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
Antimicrosomal and antithyroglobulin

8. What is a type I hypersensitivity reaction? What is atopic?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Yes
Anti glutamate carboxylase and anti insulin
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

9. which cells have more complete tolerance - B or T cells?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
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 mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after

10. What are the autoantibodies for hashimotos?
isotype
Antimicrosomal and antithyroglobulin
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
Anti U1 RNP (ribonucleoprotein)

11. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Yes
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
IL 4 - 5 - 10 - 6
Th cells fail to produce interferon gamma; a lot of IgE

12. Describe complement dependent Type II hypersensitivity. Give an example.
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
CD21 on B cells (although there is T cell lymphocytosis in EBV)

13. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Immunosuppression after kidney transplantation
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
pentamer

14. IgM can exist as a _______ also
pentamer
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
Antidote for digoxin intoxication
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

15. Which diseases are associated with DR4?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
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
DM type I and RA
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

16. Describe the Mannose Lectin pathway
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
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory 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
Anti topoisomerase

17. which type of immunity is slow but long lasting? as opposed to...
dimer
opsonizes
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
Active; passive - fast but short half life (3 weeks!)

18. What lymph node drains the scrotum?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
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
Superficial inguinal
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

19. What lymph node drains the anal canal (below the pectinate line)?
Superficial inguinal
Celiac
A chemotactic factor for neutrophils
Anemias (esp due to renal failure)

20. A lymph node is a ________ lymphoid organ.
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
secondary
isotype
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids

21. What is the presentation of hyperIgM syndrome?
Severe pyogenic infections early in life
Anti glutamate carboxylase and anti insulin
Its a serine protease that activates apoptosis; NK and CD8
Type IV

22. What kinds of receptors activate innate immunity?
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
TLR ad nuclear receptors
Daclizumab; prevent ACUTE rejection of renal transplant

23. what secretes IL 4?
T cell precursor
isotype
NK cells
Basophils! THey want IG E class switch!

24. what bacteria are a splenectomy patient most susceptible to? why?
Fab portion
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
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
B - T - and NK cells

25. What are the main Cell surface proteins on T cells?
Hereditary angioedema; PNH
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Intracellular pathogens (acute and chronic viruses and virally induced cancers)

26. What does IgA pick up from epithelial cells before being secreted?
not Ab mediated
Secretory component
Viral neutralization of igM and IgG!
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

27. 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
A - B - C; all the D's
Viral neutralization of igM and IgG!
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

28. What does CD16 on NK cells do?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Bind FcG for antibody dependent cellular cytotoxicity
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
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

29. What lymph node drains the rectum (above the pectinate line)?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Internal iliac
acute phase reactants

30. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

31. What does granulysin do?
Anti topoisomerase
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
In the germinal center of secondary follicles (In the paler center)

32. is IgM an opsonizer?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Negative!
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

33. What happens in a deficiency of C3?
Axillary
Immunoflourescent staining of tissue biopsies
Immunosuppression after kidney transplantation
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

34. Give an example of someone who could get hyperacute transplant rejection.
Edema and necrosis in that region
IL 1 and IL 6
IgG
Previous transfusion; pregnant woman whose fetus had paternal antigens

35. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Not thymus - BM
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Hereditary angioedema; PNH
Remove encapsulated bacateria

36. What is the treatment of acute transplant rejection?
IgM and IgA
Negative nitroblue tetrazolium reduction test
Antibody mediated cytotoxicity; either complement dependent or complement independent
Cyclosporine - OKT3

37. Give three examples of bacteria that use antigenic variation and how.
secondary
Anti glutamate carboxylase and anti insulin
pale central germinal centers
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein

38. which interleukin receptor is required for NK development? activation?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
A j chain
IL 15; IL 12 - interferon Beta and interferon alpha
Secretory component

39. Only the _______ contribute to the Fc region
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Axillary
heavy chains
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

40. What are the main symptoms of T cell immunodeficiencies?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Anti topoisomerase
The igA found in breast milk
TNF alpha and IL1

41. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
...
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

42. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
Superficial inguinal
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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

43. What lymph node drains the testes?
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)
Para aortic
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
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

44. what happens in a deficiency of C1 esterase inhibitor? DAF?
Hereditary angioedema; PNH
Acts as second signal on B cells to induce class switching to IgE and IgG
Activates Th1 helper cells; Macrophages
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

45. other than eat and bite RBCs what else do Macrophages of spleen do>
Remove encapsulated bacateria
Paracortex; viral infection
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

46. what ensure that a memory response is generated?
If there is class switching and plasma cell production (that is when memory cells are produced)
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Anti U1 RNP (ribonucleoprotein)
Immunoflourescent staining of tissue biopsies

47. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
IgM and IgA
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Anti alpha subunit 3 of collagen on type IV bm
Cross link

48. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
TLR ad nuclear receptors
Negative!
not Ab mediated
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

49. which antibody is involved in the primary response or immediate response to an antigen?
Popliteal
Receiving preformed Antibodies
opsonizes
IgM

50. What are the two signals required for B cell class switching? Which is the second signal?
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
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
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
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal