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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 some sinopulmonary infections?
A - B - C; all the D's
Axillary
Steroid responsive nephrotic syndrome
Sinusitis - otitis media - pneumonia

2. To what disease do the autoantibodies to IgG (rheumatoid factor)?
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
Rheumatic arthritis
secondary
IgG

3. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Thrombocytopenia
B - T - and NK cells

4. What is immune complex disease? give an example.
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
The patient could become cyanotic in the OR!

5. What lymph node drains the sigmoid colon?
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Inferior mesenteric
Histamine; post capillary venules - vasodilation

6. What are the autoantibodies for primary biliary cirrhosis?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Anti mitochondrial
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Superficial inguinal

7. What lymph node drains the stomach?
Celiac
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
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
RNA segment reassortment

8. What is thrombopoietin used for?
Thrombocytopenia
Alternative splicing of mRNA
...
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

9. Which type of selection of thymic development provides central tolerance?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
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
Anti IF
Negative selection

10. What does interferon gamma do? What two type of cells does it attack mostly?
...
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
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

11. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
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
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
IgA
Basophils! THey want IG E class switch!

12. 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
2 heavy chains and two light chains
Liver! (they are proteins circulating in the blood)
MHC class molecules bind to KIRS or CD94 to prevent killing

13. From where do cytokines come from?
IL 3; supports growth and differentiation of bone marrow stem cells
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
opsonizes
Lymphocytes

14. What is the pathology seen in chronic transplant rejection?
Antidesmoglein
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
IgM
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

15. How does the alternative pathway lead to MAC activation?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
No because no peptide fragment!
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

16. The ______ in the BM are DN - the DP are in the cortex of thymus
T cell precursor
Anti U1 RNP (ribonucleoprotein)
Anti mitochondrial
lowest concentration

17. Which are the only two antiinflammatory cytokines?
TGF beta and IL 10
Viral neutralization of igM and IgG!
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
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)

18. IgG...
Negative!
opsonizes
RNA segment reassortment
TLR ad nuclear receptors

19. Give an example of someone who could get hyperacute transplant rejection.
Previous transfusion; pregnant woman whose fetus had paternal antigens
Graves
Acts as second signal on B cells to induce class switching to IgE and IgG
Negative nitroblue tetrazolium reduction test

20. How is the thymus organized? what happens in each section?
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
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 :(
C5a
Into cortex and medulla; cortex is where immature T lymphocytes enter - at the corticomedullar junction is where positive and negative selection occur; and at the medulla is where the mature T lymphs - reticulin cells and hassalls corpuscles are (dea

21. What is serum sickness? give an example.
Local infection/inflammation; infection of the ln itself; metastasis
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
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
...

22. What are the mediators that mast cells release?
Histamine; post capillary venules - vasodilation
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Anti topoisomerase
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

23. Only the _______ contribute to the Fc region
heavy chains
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
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii

24. IgE has the ___________ in the serum
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
Histamine; post capillary venules - vasodilation
A recomb cytokine of IL 2; RCC and metastatic melanoma
lowest concentration

25. What links the adaptive and innate immunity?
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Complement activation (active in both)
Superficial inguinal
...

26. Which antibody mediates immunity to worms? how?
Cytokine IL 10 secreted by Th2
IgE; by activating eosinophils
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
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

27. A lymph node is a ________ lymphoid organ.
Superficial inguinal
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
C5a
secondary

28. What can cause a lymph node enlargement?
Local infection/inflammation; infection of the ln itself; metastasis
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)
Axillary
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

29. What are the main Cell surface proteins on T cells?
Histamine; post capillary venules - vasodilation
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Superficial inguinal
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

30. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
Tetanus - Botulinum - HBV - Rabies
Cytokine IL 10 secreted by Th2
All MHC 1/CD8
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

31. Which helper T cells' development is induced by IL 4? IL 12?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Th2; Th1
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
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

32. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
mesenchymal
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
Cells that stil have weird parts of their membrane that macrophages usually bite off
pathogenesis

33. __________ are a part of the innate system.
Influenza; antigenic shift; antigenic drift
lowest concentration
NK cells
Interferon gamma; Th1

34. Describe the interstitial tissue of a spleen including the sinuses. What type of cells are found in the four structures (cortex - paracortex - medulla and sinuses)?
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
By transcytosis
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
IgM and IgG

35. hat is the presentation of Jobs syndrome or Hyper IgE?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
mesenchymal
IL 15; IL 12 - interferon Beta and interferon alpha

36. What are the major functions of Antibodies?
Paracortex
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Anti viral and anti tumor
Activate macrophages

37. What cytokines are released by Th1 cells?
Interferon gamma and IL 2
S. aureus - E. Coli - aspergillus
RNA segment reassortment
Anti alpha subunit 3 of collagen on type IV bm

38. other than eat and bite RBCs what else do Macrophages of spleen do>
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Remove encapsulated bacateria
lowest concentration

39. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
The patient could become cyanotic in the OR!
not Ab mediated
Interferon gamma and IL 2
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

40. What is the toxicity of muromonab?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
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 :(
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

41. Leukocyte adhesion defect presents with...
Anti IF
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
neutrophilia!
Fab portion

42. What are target cells?
Cytokine IL 10 secreted by Th2
Anti U1 RNP (ribonucleoprotein)
Receiving preformed Antibodies
Cells that stil have weird parts of their membrane that macrophages usually bite off

43. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
Its main effect is a defect in Ab opsonization for killing
IgG
Graves
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

44. The lymphocytes are ________ origin
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Basophils! THey want IG E class switch!
mesenchymal

45. what characterizes an arthus reaction?
2 heavy chains and two light chains
Edema and necrosis in that region
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

46. What type of side chains are found on Fc region of an antibody?
Carbohydrate
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
T
Activates Th1 helper cells; Macrophages

47. What is the pathology in hyperacute transplant rejection?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Edema and necrosis in that region
Delayed type hypersensitivity
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels

48. So antibodies are the effectors for the humoral response. List some of their functions.
Stimulate the liver to release acute phase reactants
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
...

49. describe the pathogenesis of delayed type IV hypersensitivity
T cell dysfunction
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Th2; Th1
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

50. Which disease is associated withB B27?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
CRP - C3b - IgM
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Anti IF