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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. which of the hypersensitivity reactions is not Ab mediated?
Type IV
Delayed type hypersensitivity
C5a
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

2. What lymph node drains the scrotum?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Superior mesenteric
Superficial inguinal

3. What does Interferon alpha and beta do? how?
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
Superior mesenteric
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Local infection/inflammation; infection of the ln itself; metastasis

4. What are the autoantibodies for hashimotos?
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Antimicrosomal and antithyroglobulin
IgAs in mothers breast milk!

5. 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?
IgE
not Ab mediated
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
Celiac

6. other than C3a - what other complement acts as an anaphyloxin?
Superior mesenteric
All MHC 1/CD8
C5a
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

7. What is the toxicity of muromonab?
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Antibody mediated cytotoxicity; either complement dependent or complement independent
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

8. What is recomb gamma interferon used for?
encapsulated
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
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Chronic granulomatous disease

9. The ______ in the BM are DN - the DP are in the cortex of thymus
Cells that stil have weird parts of their membrane that macrophages usually bite off
T cell precursor
pale central germinal centers
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

10. What are the three types of lymphocytes?
mesenchymal
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Paracortex
B - T - and NK cells

11. IgE has the ___________ in the serum
Anti glutamate carboxylase and anti insulin
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
active complement pathway
lowest concentration

12. What happens in a secondary follicle?
IL 3; supports growth and differentiation of bone marrow stem cells
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Interferon gamma; Th1
IgA

13. What are superantigens? give two examples.
Daclizumab; prevent ACUTE rejection of renal transplant
IgM and IgD
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
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

14. The alternative pathway is the only constutively...
active complement pathway
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
Activate macrophages
Superior mesenteric

15. What is the marginal zone of the spleen? what happens there?
Hereditary angioedema; PNH
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
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
except hyperacute

16. What is a factor that is a predictor for a bad transplantation?
Anti Jo -1
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

17. What are the main cell surface proteins on B cells?
Anti alpha subunit 3 of collagen on type IV bm
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

18. Leukocyte adhesion defect presents with...
Viral neutralization of igM and IgG!
Superficial inguinal
neutrophilia!
opsonizes

19. What is the toxicity of azathioprine?
...
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Delayed type hypersensitivity
Interferon gamma; Th1

20. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Negative selection
Kill them because they have CD16 on them that recognize the FcG portion
Antibody mediated cytotoxicity; either complement dependent or complement independent
Influenza; antigenic shift; antigenic drift

21. are Th cells involved in trapping of antigens of endotoxin/LPS?
No because no peptide fragment!
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
IL 1 and IL 6
Liver! (they are proteins circulating in the blood)

22. which of the IL2 inhibitors produce nephrotoxicity? thrombocytopenia/leukopenia?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

23. What is the clinical use of Muromonab?
Immunosuppression after kidney transplantation
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!
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
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

24. How does igA cross the epithelium?
opsonizes
The patient could become cyanotic in the OR!
Severe pyogenic infections early in life
By transcytosis

25. What are the major functions of Antibodies?
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

26. what prevents NK cells from killing normal cells if their default is to kill?
T cell activation; no with CD 4 or CD 8
Sinusitis - otitis media - pneumonia
IL 1 and IL 6
MHC class molecules bind to KIRS or CD94 to prevent killing

27. Monomer in circulation - ___ when secreted
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
By transcytosis
dimer
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

28. What are the autoantibodies for sjorgens syndrome?
Anti SS- A (anti RO) and Anti SS- B
Chronic granulomatous disease
Previous transfusion; pregnant woman whose fetus had paternal antigens
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

29. What lymph node drains the lateral side of the dorsum of the foot?
T cell precursor
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
Popliteal
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

30. 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)
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
IL 1 and IL 6

31. What does granzyme do? who secretes it?
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
Chronic granulomatous disease
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
Its a serine protease that activates apoptosis; NK and CD8

32. What bugs can actually infect the lymph node itself?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Type III hypersensitivity where an exogenous antigen results in a systemic antigen antibody complex disease (takes around 5 days after exposure for the Abs to develop); immune complexes then fix in tissue and activate complement resulting in tissue d
pathogenesis
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

33. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Glycoproteins; HLA
Previous transfusion; pregnant woman whose fetus had paternal antigens
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency

34. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
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)
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Acts as second signal on B cells to induce class switching to IgE and IgG
Increases expression of MHC I and MHC II and also activates NK cells

35. can igG cross the placenta?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
...
Yes

36. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
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
Severe pyogenic infections early in life
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE

37. The two heavy chains of an antibody contribute to the...
Fab portion
Humoral
Hereditary angioedema; PNH
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

38. What are the two signals to kill for NK cells?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Interferon gamma; Th1
TGF beta and IL 10
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

39. Which Thelper cell activated Macrophages? by secreting what? what else does Th1 secrete? For what?
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
IL 3; supports growth and differentiation of bone marrow stem cells
IgM and IgG
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

40. What portion of the lymph node is not well developed in DiGeorge Syndrome?
Paracortex
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Delayed type hypersensitivity
Remove encapsulated bacateria

41. which antibody activate mast cells - basophils - and eosinophils?
Popliteal
IgE
Negative selection
Daclizumab; prevent ACUTE rejection of renal transplant

42. Which diseases are associated with DR4?
DM type I and RA
Bind FcG for antibody dependent cellular cytotoxicity
Sinusitis - otitis media - pneumonia
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

43. IgM can fix complement but...
Basophils! THey want IG E class switch!
MHC II - B7
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
cannot cross placenta

44. What is the cause of thymic aplasia? What is its presentation? What are the labs?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Anti TSh receptor
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

45. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
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!

46. which of the transplant rejections is antibody mediated? why does it occur?
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
No because no peptide fragment!
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )

47. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
Acts as second signal on B cells to induce class switching to IgE and IgG
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
2 heavy chains and two light chains

48. What is colostrum?
RNA segment reassortment
Sinusitis - otitis media - pneumonia
The igA found in breast milk
...

49. How do you test for type III hypersensitivity?
carboxy terminal
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Immunoflourescent staining of tissue biopsies

50. What lymph node drains the rectum (above the pectinate line)?
Influenza; antigenic shift; antigenic drift
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Internal iliac