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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
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 does it mean if there are igM in the serum at birth?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Activates cytotoxic CD 8 T cells as second signal
Fab portion
Carbohydrate

2. in which immunodef order do you see a lot of pus? no pus?
Anti smooth muscle
Paracortex; viral infection
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

3. What lymph node drains the upper limb?
Axillary
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
If there is class switching and plasma cell production (that is when memory cells are produced)
Complement activation (active in both)

4. What is Aldesleukin? What is it used for
DM type I
Local infection/inflammation; infection of the ln itself; metastasis
Not thymus - BM
A recomb cytokine of IL 2; RCC and metastatic melanoma

5. What are the main symptoms of B cell immunodeficiencies?
B - T - and NK cells
IL 1 and IL 6
SP infections
except hyperacute

6. What does granzyme do? who secretes it?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Delayed type hypersensitivity
Its a serine protease that activates apoptosis; NK and CD8
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

7. The lymphocytes are ________ origin
mesenchymal
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

8. A lymph node is a ________ lymphoid organ.
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
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
secondary

9. What is recomb beta interferon used for?
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
MS
IgE
The igA found in breast milk

10. Leukocyte adhesion defect presents with...
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
neutrophilia!
Superficial inguinal
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

11. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

12. What are the cell surface proteins on NK cells?
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
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
MHC I - CD16 - CD56
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

13. The alternative pathway is the only constutively...
active complement pathway
B - T - and NK cells
Active; passive - fast but short half life (3 weeks!)
A - B - C; all the D's

14. which antibodies prevent antigens from binding mucosal surfaces?
False! B cell class switching requires a second signal
IL 15; IL 12 - interferon Beta and interferon alpha
IgA
Liver! (they are proteins circulating in the blood)

15. 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?
IgM
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
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
CRP - C3b - IgM

16. What are the autoantibodies for drug induced lupus?
Immunosuppression after kidney transplantation
Cyclosporine - OKT3
Antihistone
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

17. which B and T cell disorder presents with specifically low IgM?
Negative!
Antidote for digoxin intoxication
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Wiskott Aldrich syndrome

18. Give an example of someone who could get hyperacute transplant rejection.
Previous transfusion; pregnant woman whose fetus had paternal antigens
TNF alpha and IL1
Popliteal
Cyclosporine - OKT3

19. which cytokine inhibits TH2 cells? secreted by who?
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Glycoproteins; HLA
Sinusitis - otitis media - pneumonia
Interferon gamma; Th1

20. What is the pathogenesis of a hypersensitivity reaction?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
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

21. What is the late phase reaction of anaphylaxis allergy? what mediates it?
Negative!
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
MS
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)

22. What are target cells?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Cells that stil have weird parts of their membrane that macrophages usually bite off
Macrophages - Dendritic cells - B cells
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

23. what will NK cells do to cells covered in IgG Ab? why?
DM type I
Delayed type hypersensitivity
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Kill them because they have CD16 on them that recognize the FcG portion

24. which type of immunity is slow but long lasting? as opposed to...
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Active; passive - fast but short half life (3 weeks!)
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
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

25. Complements are...
acute phase reactants
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Anti alpha subunit 3 of collagen on type IV bm
In the germinal center of secondary follicles (In the paler center)

26. which cells have more complete tolerance - B or T cells?
Lymphocytes
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
T
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

27. which of the IL2 inhibitors produce nephrotoxicity? thrombocytopenia/leukopenia?
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
Superior mesenteric
Macrophages - Dendritic cells - B cells
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

28. 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
A - B - C; all the D's
Pernicious Anemia and Hashimotos
When you select for which MHC it will have; take out the lymphs that self react

29. IgE has the ___________ in the serum
lowest concentration
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation

30. which of the hypersensitivity reactions is not Ab mediated?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Type IV
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
Anti Jo -1

31. other than C3a - what other complement acts as an anaphyloxin?
C5a
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

32. which antibody activate mast cells - basophils - and eosinophils?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
T cell precursor
IgE
Interferon gamma and IL 2

33. What are the sinusoids of the spleen? What is the difference between a spleen and a lymph node?
Anti Jo -1
Chronic granulomatous disease
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
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages

34. What are the cell surface proteins for Macrophages? which two are for opsonins?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
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
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

35. What lymph node drains the breast?
Antidesmoglein
Axillary
Previous transfusion; pregnant woman whose fetus had paternal antigens
Cross link

36. describe the classic complement pathway.
Celiac
Yes
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

37. describe the pathogenesis of delayed type IV hypersensitivity
IL 4 - 5 - 10 - 6
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
MS - hay fever - SLE - goodpastures
T cells react to the angtigen and activate leukocyted (macrophage acitivation)

38. What is the white pulp of the spleen?
IgE
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Glycoproteins; HLA
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

39. where do somatic hypermutation and class switching occur?
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
In the germinal center of secondary follicles (In the paler center)
Stimulate the liver to release acute phase reactants
pentamer

40. What is chronic mucocutaneous candidiasis d/t?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
T cell dysfunction
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Not thymus - BM

41. What are the autoantibodies for wegeners granulomatosis?
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 :(
Interferon gamma; Th1
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

42. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
Superficial inguinal
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
Negative!
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

43. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
IgAs in mothers breast milk!
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

44. How does the alternative pathway lead to MAC activation?
The patient could become cyanotic in the OR!
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
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

45. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein

46. IgM can exist as a _______ also
A recomb cytokine of IL 2; RCC and metastatic melanoma
pentamer
MHC II - B7
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

47. What are the symptoms of serum sickness?
secondary
Superior mesenteric
encapsulated
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

48. Describe the capsular structure of a lymph node; What are the functions of the LN?
Activate macrophages
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
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

49. explain the process from beginning (ie phagocytosis of the peptide) to end of how Abs are formed in Goodpasteurs.
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
Antidote for digoxin intoxication
IgE
Antibody mediated cytotoxicity; either complement dependent or complement independent

50. Which are the only two antiinflammatory cytokines?
TGF beta and IL 10
Anti TSh receptor
Fc
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor