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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 are the major functions of Antibodies?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
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
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Superficial inguinal

2. what characterizes an arthus reaction?
Edema and necrosis in that region
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
All MHC 1/CD8
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

3. what ensure that a memory response is generated?
If there is class switching and plasma cell production (that is when memory cells are produced)
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
...
Complement activation (active in both)

4. What is Aldesleukin? What is it used for
IgM and IgA
RNA segment reassortment
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
A recomb cytokine of IL 2; RCC and metastatic melanoma

5. Type Iv hypersensitivity is...
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
Activates cytotoxic CD 8 T cells as second signal
delayed!
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

6. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
Anti U1 RNP (ribonucleoprotein)
Alternative splicing of mRNA
TGF beta and IL 10
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

7. What lymph node drains the thigh?
Fc
Superficial inguinal
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
MHC I; from RER with help of the B2 microglobulin

8. What are the cell surface proteins for Macrophages? which two are for opsonins?
MHC I; from RER with help of the B2 microglobulin
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
2 heavy chains and two light chains
T cell precursor

9. What does IL 10 do? who is secreted by?
NK cells
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

10. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
type four
Negative selection
Axillary
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

11. What does IL 2 do?
Tetanus - Botulinum - HBV - Rabies
Activates cytotoxic CD 8 T cells as second signal
mesenchymal
MHC I; from RER with help of the B2 microglobulin

12. 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?
Liver! (they are proteins circulating in the blood)
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
TGF beta and IL 10

13. describe the classic complement pathway.
Activates cytotoxic CD 8 T cells as second signal
Immunoflourescent staining of tissue biopsies
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
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

14. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
Lymphocytes
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
Cyclosporine - OKT3

15. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
DM type I and RA

16. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
IL 3; supports growth and differentiation of bone marrow stem cells
Steroid responsive nephrotic syndrome
TNF alpha and IL1
Anti SS- A (anti RO) and Anti SS- B

17. What is oprelevkin? and What is it used for?
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
opsonizes
active complement pathway
Recom IL 11; thrombocytopenia

18. What is the main cytokine that activates eosinophils?
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
Its main effect is a defect in Ab opsonization for killing
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
IL 5

19. What does interferon gamma do to be antiviral?
Type IV
Increases expression of MHC I and MHC II and also activates NK cells
Antidote for digoxin intoxication
Anti alpha subunit 3 of collagen on type IV bm

20. How do you test for type III hypersensitivity?
isotype
Immunoflourescent staining of tissue biopsies
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
NK cells

21. Which diseases are associated with DR4?
DM type I and RA
Wiskott Aldrich syndrome
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
Th cells fail to produce interferon gamma; a lot of IgE

22. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
False! B cell class switching requires a second signal

23. What cytokines are released by Th1 cells?
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Interferon gamma and IL 2
T cell precursor

24. What is the pathogenesis of chronic transplant rejection? When does it occur? is it reversible?
The igA found in breast milk
Viral neutralization of igM and IgG!
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 :(
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

25. What can cause a lymph node enlargement?
Histamine; post capillary venules - vasodilation
Lymphocytes
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Local infection/inflammation; infection of the ln itself; metastasis

26. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Its main effect is a defect in Ab opsonization for killing

27. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Glycoproteins; HLA
Hereditary angioedema; PNH
When you select for which MHC it will have; take out the lymphs that self react
Antibody mediated cytotoxicity; either complement dependent or complement independent

28. What are the cell surface proteins on NK cells?
MHC I - CD16 - CD56
Superficial inguinal
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Edema and necrosis in that region

29. give an example of how influenza does a major antigenic shift.
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
RNA segment reassortment
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Complement activation (active in both)

30. What are the PALS?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Viral neutralization of igM and IgG!
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

31. Give three examples of bacteria that use antigenic variation and how.
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
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IL 5
Macrophages - Dendritic cells - B cells

32. __________ are a part of the innate system.
...
Delayed type hypersensitivity
Pernicious Anemia and Hashimotos
NK cells

33. which antibody is involved in the primary response or immediate response to an antigen?
IgM
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
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
IgAs in mothers breast milk!

34. what secretes IL 4?
Wiskott Aldrich syndrome
Basophils! THey want IG E class switch!
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
Fab portion

35. In thymic development - What is the positive selection? negative selections?
When you select for which MHC it will have; take out the lymphs that self react
Cytokine IL 10 secreted by Th2
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor

36. What is three common causes of severe combined immunodef? What is the result of all three?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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 3; supports growth and differentiation of bone marrow stem cells

37. What are the symptoms of serum sickness?
carboxy terminal
...
IL 15; IL 12 - interferon Beta and interferon alpha
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

38. The ______ in the BM are DN - the DP are in the cortex of thymus
T cell precursor
Interferon gamma and IL 2
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Anti glutamate carboxylase and anti insulin

39. Which diseases are associated with DR5?
Pernicious Anemia and Hashimotos
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Fc
Previous transfusion; pregnant woman whose fetus had paternal antigens

40. what bacteria are a splenectomy patient most susceptible to? why?
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
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
Influenza; antigenic shift; antigenic drift
Hereditary angioedema; PNH

41. If an antigen lacks a peptide component How does the adaptive immunity attack it? What type of response is this called. give an example of bugs that do this. what implications does this have on splenectomy?
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
B - T - and NK cells
Superficial inguinal
Anti SS- A (anti RO) and Anti SS- B

42. How does complement link innate and adaptive?
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
When you select for which MHC it will have; take out the lymphs that self react
DM type I
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

43. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Acts as second signal on B cells to induce class switching to IgE and IgG
Sinusitis - otitis media - pneumonia
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

44. Which HLA's are included in MHC I? MHC II?

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45. What does granzyme do? who secretes it?
Cells that stil have weird parts of their membrane that macrophages usually bite off
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Its a serine protease that activates apoptosis; NK and CD8
Anti glutamate carboxylase and anti insulin

46. What part of the lymph node specifically expands during a cellular immune response? when would this occur?
Receiving preformed Antibodies
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Paracortex; viral infection
Antimicrosomal and antithyroglobulin

47. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
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
Cross link
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
IL 15; IL 12 - interferon Beta and interferon alpha

48. What are the autoantibodies for pernicious anemia?
Anti IF
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Not thymus - BM

49. which antibody activate mast cells - basophils - and eosinophils?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
IgE
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Influenza; antigenic shift; antigenic drift

50. The secondary follicles have __________; primary follicles are dense
pale central germinal centers
TNF alpha and IL1
T cell precursor
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata