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. Type IV hypersensitivity is i...
delayed!
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
not Ab mediated
CD21 on B cells (although there is T cell lymphocytosis in EBV)

2. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
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
...
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
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

3. What is colostrum?
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
The igA found in breast milk
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Cells that stil have weird parts of their membrane that macrophages usually bite off

4. What does IL 4 do?
IL 4
Lymphocytes
Axillary
Acts as second signal on B cells to induce class switching to IgE and IgG

5. What are the autoantibodies for hashimotos?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
RNA segment reassortment
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
Antimicrosomal and antithyroglobulin

6. What are the symptoms of serum sickness?
isotype
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Viral neutralization of igM and IgG!
In the germinal center of secondary follicles (In the paler center)

7. Which disease is associated withB B27?
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Carbohydrate
IgG

8. What is the pathology of acute transplant rejection? is it reversible?
A j chain
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
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

9. From where do cytokines come from?
By transcytosis
not Ab mediated
Lymphocytes
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

10. Which disease is associated with HLA A3?
MHC I - CD16 - CD56
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
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
Hemochromatosis

11. What are howell jolly bodies?
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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
heavy chains
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells

12. IgM can exist as a _______ also
Stimulate the liver to release acute phase reactants
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
pentamer
CRP - C3b - IgM

13. What is the presentation of common variable immunodef? and What are 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)
IL 3; supports growth and differentiation of bone marrow stem cells
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
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

14. What are some catalase positive organisms?
IgAs in mothers breast milk!
S. aureus - E. Coli - aspergillus
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
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

15. which type of immunity is slow but long lasting? as opposed to...
Active; passive - fast but short half life (3 weeks!)
Liver! (they are proteins circulating in the blood)
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Previous transfusion; pregnant woman whose fetus had paternal antigens

16. What is the result of an IL 12 deficiency? What is the presentation? What are the labs?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Activate macrophages
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

17. Name the three opsonins
Anti topoisomerase
Influenza; antigenic shift; antigenic drift
CRP - C3b - IgM
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

18. What are the two signals required for T cells? what happens after?
Superior mesenteric
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
IgA

19. which of the transplant rejections is antibody mediated? why does it occur?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
secondary
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

20. What is the defect in Brutons agammaglobulinemia? What is its effect on B cells? What is its inheritance pattern?
Anemias (esp due to renal failure)
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

21. What is the pathogenesis of a candida skin test?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Delayed type hypersensitivity
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
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)

22. What does granzyme do? who secretes it?
delayed!
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Its a serine protease that activates apoptosis; NK and CD8
Anti alpha subunit 3 of collagen on type IV bm

23. ________ regulate the cell mediated response.
Its main effect is a defect in Ab opsonization for killing
IgAs in mothers breast milk!
Humoral
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy

24. The pathogenesis of contact dermatitis is ________ hypersensitivity
type four
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
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

25. 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
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
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
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

26. What happens in a secondary follicle?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Stimulate the liver to release acute phase reactants
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

27. The idiotype; the Fc portion determines the...
Secretory component
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
isotype
2 heavy chains and two light chains

28. What is the white pulp of the spleen?
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
Activates cytotoxic CD 8 T cells as second signal
delayed!
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

29. What is the most common example of passive immunity?
Graves
IgAs in mothers breast milk!
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
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles

30. Monomer in circulation - ___ when secreted
Antimicrosomal and antithyroglobulin
dimer
Remove encapsulated bacateria
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

31. are Th cells involved in trapping of antigens of endotoxin/LPS?
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
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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
No because no peptide fragment!

32. What is the main cytokine that activates eosinophils?
IL 5
Basophils! THey want IG E class switch!
Active; passive - fast but short half life (3 weeks!)
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

33. What does IL 2 do?
Activates cytotoxic CD 8 T cells as second signal
T cell activation; no with CD 4 or CD 8
Its a serine protease that activates apoptosis; NK and CD8
pathogenesis

34. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Thrombocytopenia
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)

35. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
By transcytosis
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
carboxy terminal
Glycoproteins; HLA

36. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Active; passive - fast but short half life (3 weeks!)
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

37. which interleukin receptor is required for NK development? activation?
IL 15; IL 12 - interferon Beta and interferon alpha
heavy chains
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

38. which cytokine inhibits TH2 cells? secreted by who?
T cell dysfunction
Interferon gamma; Th1
DM type I and RA
IgG

39. Which are the only two antiinflammatory cytokines?
Para aortic
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
TGF beta and IL 10
Graves

40. What is Aldesleukin? What is it used for
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
Increases expression of MHC I and MHC II and also activates NK cells
A recomb cytokine of IL 2; RCC and metastatic melanoma
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

41. describe the classic complement pathway.
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Anti topoisomerase
Anti smooth muscle
Para aortic

42. What do multimeric antibodies require for assembly?
A j chain
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
MS - hay fever - SLE - goodpastures
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 lymph node drains the sigmoid colon?
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
cannot cross placenta
Inferior mesenteric

44. Describe complement dependent Type II hypersensitivity. Give an example.
Daclizumab; prevent ACUTE rejection of renal transplant
TNF alpha and IL1
pentamer
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

45. What lymph node drains the stomach?
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!
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Celiac
Interferon gamma; Th1

46. What are superantigens? give two examples.
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
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Th cells fail to produce interferon gamma; a lot of IgE
Edema and necrosis in that region

47. Which disease is associated with DR7?
Steroid responsive nephrotic syndrome
Antibody mediated cytotoxicity; either complement dependent or complement independent
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)
MHC I - CD16 - CD56

48. What is the cause of thymic aplasia? What is its presentation? What are the labs?
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
Lymphocytes
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
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

49. Which antibody mediates immunity to worms? how?
Immunoflourescent staining of tissue biopsies
opsonizes
IgE; by activating eosinophils
In the germinal center of secondary follicles (In the paler center)

50. what bacteria are a splenectomy patient most susceptible to? why?
pathogenesis
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
Viral neutralization of igM and IgG!
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!

Test your basic knowledge |

USMLE Step 1 Immunology

Top Scores

Link to This Test

Related Subjects