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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. Only the _______ contribute to the Fc region
heavy chains
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Chronic granulomatous disease
TLR ad nuclear receptors

2. which of the IL2 inhibitors produce nephrotoxicity? thrombocytopenia/leukopenia?
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
active complement pathway
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
IgG

3. What are some catalase positive organisms?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
S. aureus - E. Coli - aspergillus

4. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Activate macrophages
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
By transcytosis
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

5. 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?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
encapsulated

6. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
CRP - C3b - IgM
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

7. What is the clinical use for sirolimus? what should you combine it with?
IgG
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
not Ab mediated
Acts as second signal on B cells to induce class switching to IgE and IgG

8. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Barrel hoop basement membrane fenestrations
If there is class switching and plasma cell production (that is when memory cells are produced)
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

9. What are C1 - C2 - C3 - C4 important for?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Receiving preformed Antibodies
Kill them because they have CD16 on them that recognize the FcG portion
Viral neutralization of igM and IgG!

10. How is sirolimus different from tacrolimus?
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
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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

11. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
IgG
Wiskott Aldrich syndrome
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

12. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
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
Remove encapsulated bacateria
When you select for which MHC it will have; take out the lymphs that self react
All MHC 1/CD8

13. What are the autoantibodies for drug induced lupus?
Antihistone
Hemochromatosis
IgE
Antibody mediated cytotoxicity; either complement dependent or complement independent

14. Monomer in circulation - ___ when secreted
C5a
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
dimer
Cytokine IL 10 secreted by Th2

15. What is the treatment of acute transplant rejection?
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
Anemias (esp due to renal failure)
Cyclosporine - OKT3
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

16. Which is the main antibody that provides passive immunity to infants?
encapsulated
IgG
Receiving preformed Antibodies
IgE

17. IgM can fix complement but...
S. aureus - E. Coli - aspergillus
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
cannot cross placenta
Tetanus - Botulinum - HBV - Rabies

18. For which toxins are preformed antibodies (passive) given?
Kill them because they have CD16 on them that recognize the FcG portion
IgA
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Tetanus - Botulinum - HBV - Rabies

19. What is immune complex disease? give an example.
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

20. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
A - B - C; all the D's
Superficial inguinal
Superior mesenteric
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

21. Which are the only two antiinflammatory cytokines?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Superior mesenteric
TGF beta and IL 10
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

22. 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)
MHC class molecules bind to KIRS or CD94 to prevent killing
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
B - T - and NK cells

23. The alternative pathway is the only constutively...
active complement pathway
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
Immunoflourescent staining of tissue biopsies
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

24. What are the PALS?
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Anti SS- A (anti RO) and Anti SS- B
CRP - C3b - IgM

25. What is the pathogenesis of a hypersensitivity reaction?
Remove encapsulated bacateria
IL 5
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 recomb cytokine of IL 2; RCC and metastatic melanoma

26. What are the two signals to kill for NK cells?
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids

27. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
except hyperacute
MHC II - B7

28. what secretes IL 4?
Basophils! THey want IG E class switch!
lowest concentration
Daclizumab; prevent ACUTE rejection of renal transplant
CRP - C3b - IgM

29. what cell surface marker is used for NK cells as it is unique to them?
IgM
CD56
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Anti TSh receptor

30. ________ regulate the cell mediated response.
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
mesenchymal
Humoral
C5a

31. What are the autoantibodies for Celiac disease?
CRP - C3b - IgM
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Superficial inguinal

32. What happens when a T helper cell in the paracortical section encounters an antigen? a cytotoxic t cell? a B cell in the cortical section?
A j chain
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
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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

33. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
except hyperacute
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Pernicious Anemia and Hashimotos
MHC II - B7

34. What does IgA pick up from epithelial cells before being secreted?
Stimulate the liver to release acute phase reactants
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Fc
Secretory component

35. What are the three types of lymphocytes?
Complement activation (active in both)
Axillary
B - T - and NK cells
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

36. What is epo 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)
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Anemias (esp due to renal failure)
Type IV

37. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
not Ab mediated
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

38. What is anergy? why does this occur?
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
Influenza; antigenic shift; antigenic drift
2 heavy chains and two light chains
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

39. The secondary follicles have __________; primary follicles are dense
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
B - T - and NK cells
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
pale central germinal centers

40. __________ are a part of the innate system.
2 heavy chains and two light chains
NK cells
When you select for which MHC it will have; take out the lymphs that self react
Anti mitochondrial

41. What are the main Cell surface proteins on T cells?
IgG
Its a serine protease that activates apoptosis; NK and CD8
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
When you select for which MHC it will have; take out the lymphs that self react

42. What are the main symptoms of B cell immunodeficiencies?
TGF beta and IL 10
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
SP infections
Secretory component

43. What is recomb alpha interferon used for?
Immunosuppression after kidney transplantation
Bind FcG for antibody dependent cellular cytotoxicity
DM type I
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

44. What are the three immune privileged sites? why are they called that? what happens after infection in these areas?
Fc
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
Its main effect is a defect in Ab opsonization for killing
Tetanus - Botulinum - HBV - Rabies

45. What does it mean if there are igM in the serum at birth?
False! B cell class switching requires a second signal
IgM
Anti mitochondrial
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

46. 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)?
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
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
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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

47. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Cytokine IL 10 secreted by Th2
Pernicious Anemia and Hashimotos
A j chain
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

48. IgE has the ___________ in the serum
Steroid responsive nephrotic syndrome
lowest concentration
Active; passive - fast but short half life (3 weeks!)
MHC I; from RER with help of the B2 microglobulin

49. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
Bind FcG for antibody dependent cellular cytotoxicity
Anti glutamate carboxylase and anti insulin
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
SP infections

50. The pathogenesis of contact dermatitis is ________ hypersensitivity
Receiving preformed Antibodies
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
type four
Its main effect is a defect in Ab opsonization for killing