Test your basic knowledge |

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. How do you test for chronic granulomatous disease?
IgA
Negative nitroblue tetrazolium reduction test
Type IV
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

2. Which disease is associated with DR7?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Anti mitochondrial
Steroid responsive nephrotic syndrome
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

3. If the alternative pathway is constitively active - how come normal cells don't get attacked with MAC?
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
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
Anemias (esp due to renal failure)
T cell activation; no with CD 4 or CD 8

4. What are the autoantibodies for scleroderma (CREST)? scleroderma diffuse?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

5. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Axillary

6. What is anergy? why does this occur?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B 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
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

7. What is the mechanism for sirolimus? what else it known as?
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
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
carboxy terminal
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

8. Describe complement dependent Type II hypersensitivity. Give an example.
except hyperacute
IgM or IgG antibodies coat the antigen and result in activation of MAC complex via the classical pathway OR fixed macrophages in the spleen phagoctyose the opsonized (C3b or igG) antigens - ex penicillin reaction; IgM AIHA - anti B IgMs in a group A
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
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

9. The lymphocytes are ________ origin
T cell dysfunction
Local infection/inflammation; infection of the ln itself; metastasis
mesenchymal
Its main effect is a defect in Ab opsonization for killing

10. What type of fenestrations are found in the red pulp of the spleen?
Wiskott Aldrich syndrome
IgE
not Ab mediated
Barrel hoop basement membrane fenestrations

11. What does granzyme do? who secretes it?
Anti U1 RNP (ribonucleoprotein)
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
Negative nitroblue tetrazolium reduction test
Its a serine protease that activates apoptosis; NK and CD8

12. other than C3a - what other complement acts as an anaphyloxin?
IgG
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
C5a
Cells that stil have weird parts of their membrane that macrophages usually bite off

13. From where do cytokines come from?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Fc
Not thymus - BM
Lymphocytes

14. What do multimeric antibodies require for assembly?
A j chain
pale central germinal centers
Para aortic
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

15. which immunodeficiency presents with delayed separation of the umbilicus? ataxia? telangiectasia?albinism? anaphylaxis on exposure to blood products with IgA? tetany?retained primary teeth? peripheral neuropathy?
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
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
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi

16. What is the pathogenesis of chronic transplant rejection? When does it occur? is it reversible?
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 :(
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Anti Jo -1

17. How is i Th1 helper cell inhibited?
Cytokine IL 10 secreted by Th2
Humoral
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
Interferon gamma; Th1

18. The idiotype; the Fc portion determines the...
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Activate macrophages
isotype

19. which B and T cell disorder presents with specifically low IgM?
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
Wiskott Aldrich syndrome
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Cells that stil have weird parts of their membrane that macrophages usually bite off

20. What is the autoantibody for SLE that is nonspecific? Specific?
IgG
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Basophils! THey want IG E class switch!
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

21. What are the three types of APCs?
Kill them because they have CD16 on them that recognize the FcG portion
Macrophages - Dendritic cells - B cells
Receiving preformed Antibodies
Superior mesenteric

22. in which immunodef order do you see a lot of pus? no pus?
Th cells fail to produce interferon gamma; a lot of IgE
Interferon gamma and IL 2
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

23. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
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
Cross link
Yes
IL 4 - 5 - 10 - 6

24. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
When you select for which MHC it will have; take out the lymphs that self react
Cyclosporine - OKT3
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
Negative selection

25. which type of immunity is slow but long lasting? as opposed to...
Active; passive - fast but short half life (3 weeks!)
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
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
Viral neutralization of igM and IgG!

26. What are the two signals required for Th1 cells? what happens after then activated?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
All MHC 1/CD8
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
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

27. Which type of selection of thymic development provides central tolerance?
Negative selection
Anti viral and anti tumor
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

28. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
except hyperacute
CRP - C3b - IgM

29. What is the presentation of hyperIgM syndrome?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Cross link
Antimicrosomal and antithyroglobulin
Severe pyogenic infections early in life

30. What is the white pulp of the spleen?
MAC (membrane attack complex) Which is activated by C5b - C9 and results in lysis and cytoxicity by creating pores in the target membrane; encapsulated organisms (S. pnuemonia - H.influenzae - B perfussis for example) and other organisms with non pep
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
A j chain
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)

31. In order to produce Antibodies - does the antigen have to be phagocytosed? give an example with a bug and an autoimmune (type II hypersensitivity for example).
Its a serine protease that activates apoptosis; NK and CD8
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
No! That is why they are different from T cells - they can recognize antigens in free solution; if a bug has a peptide fragment that a mature naive B cell recognizes it will bind to it and cause activation - it then gets activated into a plasma cell!
Superficial inguinal

32. What is thrombopoietin used for?
IgE; by activating eosinophils
Thrombocytopenia
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
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

33. What are the four steps in phagocytosis? What are the four disease that correspond to each step?
type four
Pernicious Anemia and Hashimotos
The igA found in breast milk
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

34. What are the autoantibodies for Celiac disease?
Delayed type hypersensitivity
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
IgE
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)

35. For which toxins are preformed antibodies (passive) given?
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
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Tetanus - Botulinum - HBV - Rabies
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

36. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
Receiving preformed Antibodies

37. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens

38. What is the pathology in hyperacute transplant rejection?
Antidesmoglein
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
Anti SS- A (anti RO) and Anti SS- B

39. What is the common variable immunodeficiency ? How is it different from Brutons?
Histamine; post capillary venules - vasodilation
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

40. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Rheumatic arthritis
Activates Th1 helper cells; Macrophages
Steroid responsive nephrotic syndrome
Fab portion

41. What is passive immunity?
Axillary
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs
Receiving preformed Antibodies

42. What is the presentation of common variable immunodef? and What are the labs?
Macrophages - Dendritic cells - B cells
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
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
encapsulated

43. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)

44. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
IgE
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
...
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy

45. which cytokine inhibits TH2 cells? secreted by who?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Interferon gamma; Th1

46. To what portion of the Antibody do the complements bind?
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Immunoflourescent staining of tissue biopsies
IgG
Fc

47. What are the autoantibodies for other vasculitides?
Glycoproteins; HLA
mesenchymal
Para aortic
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

48. Only the _______ contribute to the Fc region
IgM and IgD
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
Interferon gamma; Th1
heavy chains

49. Which is the most abundant antibody in blood?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Local infection/inflammation; infection of the ln itself; metastasis
IgG

50. What is the presentation of scid? treatment?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
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
Not thymus - BM
A chemotactic factor for neutrophils