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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. What are the main Cell surface proteins on T cells?
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)
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
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

2. 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)?
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Pernicious Anemia and Hashimotos
acute phase reactants
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

3. What is the white pulp of the spleen?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T 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
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells

4. What lymph node drains the thigh?
Axillary
All MHC 1/CD8
Superficial inguinal
Remove encapsulated bacateria

5. What is a factor that is a predictor for a bad 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!
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
except hyperacute
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs

6. What are the two signals required for B cell class switching? Which is the second signal?
Anti SS- A (anti RO) and Anti SS- B
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
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

7. 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
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Axillary
Superficial inguinal

8. Name the three opsonins
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
CRP - C3b - IgM

9. What is the presentation of scid? treatment?
Liver! (they are proteins circulating in the blood)
Barrel hoop basement membrane fenestrations
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)

10. Often bacteria are associated with being killed by humoral immunity. Name some bugs that require cell mediated immunity because they evade humoral response
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
IgM and IgD
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

11. Describe the complement independent Type II hypersenstivity reaction. Give an example.
Daclizumab; prevent ACUTE rejection of renal transplant
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
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
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

12. What is recomb gamma interferon used for?
IgM and IgA
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
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
Chronic granulomatous disease

13. What lymph node drains the anal canal (below the pectinate line)?
IgE; by activating eosinophils
Daclizumab; prevent ACUTE rejection of renal transplant
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
Superficial inguinal

14. What amine is the main chemical mediator released by mast cells? Where does it act What does it result in?
Histamine; post capillary venules - vasodilation
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
IL 4 - 5 - 10 - 6
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated

15. What are the autoantibodies for drug induced lupus?
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
TGF beta and IL 10
Antihistone
2 heavy chains and two light chains

16. What does interferon gamma do? What two type of cells does it attack mostly?
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
CRP - C3b - IgM
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
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. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
except hyperacute
lowest concentration
The patient could become cyanotic in the OR!

18. What is epo used for?
Anemias (esp due to renal failure)
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Anti glutamate carboxylase and anti insulin
IgE

19. Which disease is associated with DR7?
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
IL 4
False! B cell class switching requires a second signal
Steroid responsive nephrotic syndrome

20. which antibody is involved in the primary response or immediate response to an antigen?
IgM
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
Recom IL 11; thrombocytopenia
SP infections

21. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
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
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
IgA
CRP - C3b - IgM

22. which antibodies can bind complement?
IgM and IgG
A chemotactic factor for neutrophils
T cell activation; no with CD 4 or CD 8
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

23. which cytokine inhibits TH2 cells? secreted by who?
Interferon gamma; Th1
not Ab mediated
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
IL 15; IL 12 - interferon Beta and interferon alpha

24. What is the presentation of Brutons agammaglobulinemia?
IgM and IgA
CRP - C3b - IgM
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect
pale central germinal centers

25. What are the autoantibodies for primary biliary cirrhosis?
Bind FcG for antibody dependent cellular cytotoxicity
Paracortex; viral infection
Negative nitroblue tetrazolium reduction test
Anti mitochondrial

26. What are howell jolly bodies?
lowest concentration
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
Acts as second signal on B cells to induce class switching to IgE and IgG
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages

27. what results in symptoms of shock in an acute hemolytic transfusion reaction?
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
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
Wiskott Aldrich syndrome

28. What is an example of a parasite showing antigenic variation?
Alternative splicing of mRNA
Secretory component
Popliteal
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)

29. Which helper T cells' development is induced by IL 4? IL 12?
Th2; Th1
IL 1 and IL 6
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis

30. What does interferon gamma do to be antiviral?
Increases expression of MHC I and MHC II and also activates NK cells
pentamer
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
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

31. IgM can fix complement but...
cannot cross placenta
Thrombocytopenia
Celiac
Stimulate the liver to release acute phase reactants

32. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
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
Anti alpha subunit 3 of collagen on type IV bm

33. What are the T cell functions?
Superior mesenteric
Activates cytotoxic CD 8 T cells as second signal
delayed!
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

34. Name 5 ways Antibody diversity is generated?
Local infection/inflammation; infection of the ln itself; metastasis
TLR ad nuclear receptors
Anti smooth muscle
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

35. How does complement link innate and adaptive?
Negative nitroblue tetrazolium reduction test
CD56
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
SP infections

36. The pathogenesis of contact dermatitis is ________ hypersensitivity
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
type four
A recomb cytokine of IL 2; RCC and metastatic melanoma

37. what happens in order for class switching to occur (after being activated by IL and cd40 L)?
Alternative splicing of mRNA
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Anti viral and anti tumor
Anti TSh receptor

38. __________ are a part of the innate system.
NK cells
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Into cortex and medulla; cortex is where immature T lymphocytes enter - at the corticomedullar junction is where positive and negative selection occur; and at the medulla is where the mature T lymphs - reticulin cells and hassalls corpuscles are (dea
DM type I

39. What links the adaptive and innate immunity?
Complement activation (active in both)
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Antimicrosomal and antithyroglobulin

40. What lymph node drains the upper limb?
Axillary
Graves
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
active complement pathway

41. Monomer in circulation - ___ when secreted
dimer
A - B - C; all the D's
Local infection/inflammation; infection of the ln itself; metastasis
...

42. What does it mean if there are igM in the serum at birth?
Sinusitis - otitis media - pneumonia
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
If there is class switching and plasma cell production (that is when memory cells are produced)
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

43. Which type of selection of thymic development provides central tolerance?
All MHC 1/CD8
Negative selection
IL 4 - 5 - 10 - 6
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

44. 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
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
IL 4
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

45. 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?
Histamine; post capillary venules - vasodilation
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
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
T

46. Which antibodies can be multimeric?
Barrel hoop basement membrane fenestrations
T
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
IgM and IgA

47. which antibody activate mast cells - basophils - and eosinophils?
IgE
No because no peptide fragment!
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
IL 5

48. What lymph node drains the rectum (above the pectinate line)?
Superficial inguinal
Internal iliac
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
S. aureus - E. Coli - aspergillus

49. what ensure that a memory response is generated?
Activates cytotoxic CD 8 T cells as second signal
If there is class switching and plasma cell production (that is when memory cells are produced)
...
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

50. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
...
Antihistone
Pernicious Anemia and Hashimotos
Interferon gamma; Th1