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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. what secretes IL 4?
IgG
TNF alpha and IL1
A - B - C; all the D's
Basophils! THey want IG E class switch!

2. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Anti viral and anti tumor
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
IgM and IgA

3. What are the autoantibodies for autoimmune hepatitis?
Axillary
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Anti smooth muscle

4. What is a type I hypersensitivity reaction? What is atopic?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Graves
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

5. What can cause a lymph node enlargement?
Celiac
Local infection/inflammation; infection of the ln itself; metastasis
C5a
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

6. The Fc region is found on the...
except hyperacute
carboxy terminal
Chronic granulomatous disease
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

7. 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
Anti smooth muscle
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
The igA found in breast milk

8. What does granzyme do? who secretes it?
Its a serine protease that activates apoptosis; NK and CD8
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

9. __________ are a part of the innate system.
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
TNF alpha and IL1
NK cells
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

10. What does IL 4 do?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
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
isotype
Acts as second signal on B cells to induce class switching to IgE and IgG

11. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!

12. What is recomb alpha interferon used for?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
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

13. 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
IgG
opsonizes
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

14. What are the autoantibodies for pemphigus bulgaris?
Antidesmoglein
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
IgA
acute phase reactants

15. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
DM type I and RA
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

16. IgE has the ___________ in the serum
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
IL 15; IL 12 - interferon Beta and interferon alpha
lowest concentration
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

17. Name two endogenous pyrogens
IL 1 and IL 6
IgE; by activating eosinophils
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

18. 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
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
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
IL 4

19. What are the two signals to kill for NK cells?
Cyclosporine - OKT3
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
opsonizes
pathogenesis

20. which antibody is involved in the primary response or immediate response to an antigen?
Activates Th1 helper cells; Macrophages
Active; passive - fast but short half life (3 weeks!)
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
IgM

21. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
...
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Chronic granulomatous disease

22. What lymph node drains the testes?
Negative nitroblue tetrazolium reduction test
Para aortic
Edema and necrosis in that region
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

23. What is the main cytokine that activates eosinophils?
Secretory component
Antidote for digoxin intoxication
IL 5
Interferon gamma and IL 2

24. What is the toxicity of muromonab?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
IgG
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
IgG

25. What are the cell surface proteins on NK cells?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Alternative splicing of mRNA
MHC I - CD16 - CD56
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

26. What is colostrum?
The igA found in breast milk
Anti viral and anti tumor
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
By transcytosis

27. can igG cross the placenta?
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
IgAs in mothers breast milk!
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
Yes

28. What happens in a deficiency of C3?
Steroid responsive nephrotic syndrome
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Wiskott Aldrich syndrome
MHC II - B7

29. What is the pathogenesis of chronic granulomatous disease; What is the presentation? What is the labs?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Celiac
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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

30. What happens in a secondary follicle?
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
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
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
MHC I; from RER with help of the B2 microglobulin

31. Which antibody mediates immunity to worms? how?
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
IgE; by activating eosinophils
Remove encapsulated bacateria

32. What is the mechanism for sirolimus? what else it known as?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
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
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
Acts as second signal on B cells to induce class switching to IgE and IgG

33. The two heavy chains of an antibody contribute to the...
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Superficial inguinal
Fab portion
A j chain

34. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
In the germinal center of secondary follicles (In the paler center)
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

35. which cells have more complete tolerance - B or T cells?
Activates Th1 helper cells; Macrophages
T
IgM and IgD
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

36. What are the autoantibodies for graves?
Anti TSh receptor
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
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

37. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Antihistone
By transcytosis
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

38. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
MS
A j chain
All MHC 1/CD8

39. What is the toxicity of azathioprine?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
...
Kill them because they have CD16 on them that recognize the FcG portion
CRP - C3b - IgM

40. What is epo used for?
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Type III hypersensitivity where an exogenous antigen results in a systemic antigen antibody complex disease (takes around 5 days after exposure for the Abs to develop); immune complexes then fix in tissue and activate complement resulting in tissue d
Anti mitochondrial
Anemias (esp due to renal failure)

41. What is the main function of IL 8?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
T cell precursor
IgG
A chemotactic factor for neutrophils

42. The lymphocytes are ________ origin
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Activates cytotoxic CD 8 T cells as second signal
mesenchymal
MS

43. How do you test for type III hypersensitivity?
Immunoflourescent staining of tissue biopsies
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
Axillary
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

44. What is the mode of inheritance of Chediak Higashi syndrome? What is the disease d/t? What does it result in? What is the presentation?
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Steroid responsive nephrotic syndrome
Axillary

45. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Th cells fail to produce interferon gamma; a lot of IgE
Anti glutamate carboxylase and anti insulin
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
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

46. IgM can exist as a _______ also
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
pentamer
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

47. In order to produce Antibodies - does the antigen have to be phagocytosed? give an example with a bug and an autoimmune (type II hypersensitivity for example).
IgAs in mothers breast milk!
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
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!
IL 5

48. which interleukin receptor is required for NK development? activation?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Local infection/inflammation; infection of the ln itself; metastasis
IL 15; IL 12 - interferon Beta and interferon alpha
Receiving preformed Antibodies

49. How do you test for chronic granulomatous disease?
Alternative splicing of mRNA
A chemotactic factor for neutrophils
Negative nitroblue tetrazolium reduction test
IgG

50. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
A recomb cytokine of IL 2; RCC and metastatic melanoma
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
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