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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 is anergy? why does this occur?
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
The patient could become cyanotic in the OR!
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

2. other than eat and bite RBCs what else do Macrophages of spleen do>
Remove encapsulated bacateria
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
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Alternative splicing of mRNA

3. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
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
All MHC 1/CD8
T cell precursor
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

4. How is i Th1 helper cell inhibited?
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Cytokine IL 10 secreted by Th2
DM type I and RA
IL 1 and IL 6

5. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
IgM
MHC class molecules bind to KIRS or CD94 to prevent killing
Daclizumab; prevent ACUTE rejection of renal transplant
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)

6. What portion of the lymph node is not well developed in DiGeorge Syndrome?
Hereditary angioedema; PNH
Paracortex
MHC I; from RER with help of the B2 microglobulin
In the germinal center of secondary follicles (In the paler center)

7. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Anti U1 RNP (ribonucleoprotein)
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
IgA
Rheumatic arthritis

8. What is passive immunity?
Receiving preformed Antibodies
Hereditary angioedema; PNH
IgG
Bind FcG for antibody dependent cellular cytotoxicity

9. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
pathogenesis
NK cells
MHC I - CD16 - CD56
Negative!

10. Leukocyte adhesion defect presents with...
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
C5a
neutrophilia!
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

11. Name the three opsonins
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
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
CRP - C3b - IgM

12. with failed maturation of B cells in Brutons agammaglobulinemia - What is its effect on immune pathways and why?
IL 4
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
Its main effect is a defect in Ab opsonization for killing
IgM and IgA

13. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
Activates cytotoxic CD 8 T cells as second signal
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
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
heavy chains

14. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

15. What is the main function of TNF alpha? How does it do this?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Antidote for digoxin intoxication

16. What does IL 10 do? who is secreted by?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
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
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
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

17. What are the autoantibodies for Celiac disease?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Antimicrosomal and antithyroglobulin

18. For which toxins are preformed antibodies (passive) given?
Tetanus - Botulinum - HBV - Rabies
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
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
isotype

19. What lymph node drains the stomach?
Celiac
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
IgE; by activating eosinophils
IgG

20. So antibodies are the effectors for the humoral response. List some of their functions.
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Anti topoisomerase
Interferon gamma and IL 2
Internal iliac

21. The secondary follicles have __________; primary follicles are dense
Antibody mediated cytotoxicity; either complement dependent or complement independent
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
pale central germinal centers
Steroid responsive nephrotic syndrome

22. Which cytokines do Th2 release and For what?
RNA segment reassortment
Axillary
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1

23. are Th cells involved in trapping of antigens of endotoxin/LPS?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
No because no peptide fragment!
Alternative splicing of mRNA
IgM

24. What is the most common selective Ig deficiency? What is the presentation?
Wiskott Aldrich syndrome
Superficial inguinal
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Its main effect is a defect in Ab opsonization for killing

25. 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)
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
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

26. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
Anti IF
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
...

27. What does IgA pick up from epithelial cells before being secreted?
...
TLR ad nuclear receptors
Secretory component
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

28. What is epo used for?
A j chain
Anemias (esp due to renal failure)
All MHC 1/CD8
CRP - C3b - IgM

29. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
Secretory component
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

30. What are MHC's necessary for? By themselves?
T cell activation; no with CD 4 or CD 8
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
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
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

31. 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?
IgG
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
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
A chemotactic factor for neutrophils

32. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Paracortex; viral infection
Anti SS- A (anti RO) and Anti SS- B

33. What are the cell surface proteins on NK cells?
Its a serine protease that activates apoptosis; NK and CD8
Lymphocytes
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
MHC I - CD16 - CD56

34. What type of side chains are found on Fc region of an antibody?
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
Daclizumab; prevent ACUTE rejection of renal transplant
Carbohydrate
Inferior mesenteric

35. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
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
Anti Ach receptor
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

36. what ensure that a memory response is generated?
All MHC 1/CD8
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
lowest concentration

37. What is the presentation of hyperIgM syndrome?
T cell activation; no with CD 4 or CD 8
A recomb cytokine of IL 2; RCC and metastatic melanoma
Severe pyogenic infections early in life
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

38. The idiotype; the Fc portion determines the...
MHC I - CD16 - CD56
isotype
CD56
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

39. What lymph node drains the sigmoid colon?
Remove encapsulated bacateria
Inferior mesenteric
IgG
Anti mitochondrial

40. What is digoxin immune Fab used for?
Antidote for digoxin intoxication
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

41. ________ regulate the cell mediated response.
IgM and IgA
IL 5
Humoral
By transcytosis

42. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
All MHC 1/CD8
2 heavy chains and two light chains
When you select for which MHC it will have; take out the lymphs that self react
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein

43. What is the main cytokine released by T cells? What does it do
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
IL 3; supports growth and differentiation of bone marrow stem cells
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

44. T/F B cells do not require a second signal
C5a
False! B cell class switching requires a second signal
...
Antihistone

45. Which diseases are associated with DR5?
Kill them because they have CD16 on them that recognize the FcG portion
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Pernicious Anemia and Hashimotos

46. What are the T cell functions?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Interferon gamma; Th1
Tetanus - Botulinum - HBV - Rabies
IgG

47. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
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
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
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

48. what characterizes an arthus reaction?
Edema and necrosis in that region
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
IgAs in mothers breast milk!
pathogenesis

49. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Fc
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
A recomb cytokine of IL 2; RCC and metastatic melanoma
MHC I; from RER with help of the B2 microglobulin

50. What does interferon gamma do? What two type of cells does it attack mostly?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
NK cells
Para aortic