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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?
IgE
Previous transfusion; pregnant woman whose fetus had paternal antigens
Type IV
SP infections

2. Describe the capsular structure of a lymph node; What are the functions of the LN?
mesenchymal
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
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
Antihistone

3. Which disease is associated withB B27?
Anti viral and anti tumor
MHC I; from RER with help of the B2 microglobulin
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
Cytokine IL 10 secreted by Th2

4. What is the pathogenesis of a candida skin test?
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
not Ab mediated
Delayed type hypersensitivity

5. what prevents NK cells from killing normal cells if their default is to kill?
MHC class molecules bind to KIRS or CD94 to prevent killing
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Anti topoisomerase
Superficial inguinal

6. What does interferon gamma do to be antiviral?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
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
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Increases expression of MHC I and MHC II and also activates NK cells

7. which interleukin receptor is required for NK development? activation?
IL 15; IL 12 - interferon Beta and interferon alpha
Celiac
2 heavy chains and two light chains
Anti IF

8. what bacteria are a splenectomy patient most susceptible to? why?
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
CD56
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids

9. What are the main symptoms of B cell immunodeficiencies?
Negative selection
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
SP infections
Carbohydrate

10. What is the marginal zone of the spleen? what happens there?
False! B cell class switching requires a second signal
DM type I
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
Previous transfusion; pregnant woman whose fetus had paternal antigens

11. What is the receptor for EBV? On what cells is that located?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
carboxy terminal
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Activate macrophages

12. What lymph node drains the rectum (above the pectinate line)?
TLR ad nuclear receptors
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
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
Internal iliac

13. What is three common causes of severe combined immunodef? What is the result of all three?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Yes
isotype
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

14. Name 5 ways Antibody diversity is generated?
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
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
Delayed type hypersensitivity
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

15. are Th cells involved in trapping of antigens of endotoxin/LPS?
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
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
No because no peptide fragment!
A - B - C; all the D's

16. Describe the complement independent Type II hypersenstivity reaction. Give an example.
lowest concentration
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Edema and necrosis in that region
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

17. What is recomb alpha interferon used for?
Anti Ach receptor
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Carbohydrate
IL 15; IL 12 - interferon Beta and interferon alpha

18. other than eat and bite RBCs what else do Macrophages of spleen do>
Anti TSh receptor
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Remove encapsulated bacateria
A j chain

19. What lymph node drains the thigh?
Superficial inguinal
Delayed type hypersensitivity
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
IL 4

20. If an antigen lacks a peptide component How does the adaptive immunity attack it? What type of response is this called. give an example of bugs that do this. what implications does this have on splenectomy?
Cyclosporine - OKT3
...
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
Antimicrosomal and antithyroglobulin

21. What is epo used for?
Chronic granulomatous disease
Anemias (esp due to renal failure)
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
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock

22. What does IL 5 do?
Activates cytotoxic CD 8 T cells as second signal
Negative!
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
Negative nitroblue tetrazolium reduction test

23. What are the autoantibodies for primary biliary cirrhosis?
Anti mitochondrial
False! B cell class switching requires a second signal
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
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

24. what characterizes an arthus reaction?
Axillary
A chemotactic factor for neutrophils
Edema and necrosis in that region
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

25. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
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
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Antidote for digoxin intoxication

26. Which helper T cells' development is induced by IL 4? IL 12?
The patient could become cyanotic in the OR!
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Th2; Th1
Paracortex

27. Which disease is associated with DR3?
Not thymus - BM
Antihistone
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
DM type I

28. What is the general structure of an Ab?
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
except hyperacute
2 heavy chains and two light chains
Superficial inguinal

29. what cytokine does basophils secrete?
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
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
IL 4
TGF beta and IL 10

30. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Receiving preformed Antibodies
Pernicious Anemia and Hashimotos
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

31. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
Edema and necrosis in that region
Influenza; antigenic shift; antigenic drift
cannot cross placenta

32. What are the autoantibodies for autoimmune hepatitis?
Internal iliac
Anti smooth muscle
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
Macrophages - Dendritic cells - B cells

33. Other than stimulating fever - what else does IL 6 do?
Immunoflourescent staining of tissue biopsies
Stimulate the liver to release acute phase reactants
...
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

34. What are some catalase positive organisms?
Interferon gamma and IL 2
IgM and IgG
DM type I and RA
S. aureus - E. Coli - aspergillus

35. How does complement link innate and adaptive?
A - B - C; all the D's
Receiving preformed Antibodies
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill

36. What type of fenestrations are found in the red pulp of the spleen?
Barrel hoop basement membrane fenestrations
Cross link
pentamer
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.

37. The pathogenesis of contact dermatitis is ________ hypersensitivity
type four
Negative nitroblue tetrazolium reduction test
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

38. What are target cells?
Liver! (they are proteins circulating in the blood)
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
When you select for which MHC it will have; take out the lymphs that self react
Cells that stil have weird parts of their membrane that macrophages usually bite off

39. What happens in a deficiency of C3?
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
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Interferon gamma and IL 2

40. The MALT/GALT are not...
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
IgG
Hemochromatosis
encapsulated

41. What two ways do you test for a type 1 hypersensitivity reaction? what will you see?
IL 5
A chemotactic factor for neutrophils
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)

42. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
The igA found in breast milk
Liver! (they are proteins circulating in the blood)
S. aureus - E. Coli - aspergillus

43. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
...
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
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

44. What lymph node drains the anal canal (below the pectinate line)?
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Tetanus - Botulinum - HBV - Rabies
Superficial inguinal
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

45. What is a factor that is a predictor for a bad transplantation?
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
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
Cyclosporine - OKT3

46. What is the monoclonal antibody to IL2 on activated T cells? What is it used for?
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Daclizumab; prevent ACUTE rejection of renal transplant
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
Edema and necrosis in that region

47. The lymphocytes are ________ origin
mesenchymal
Hemochromatosis
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
Antihistone

48. What type of side chains are found on Fc region of an antibody?
Anti viral and anti tumor
Carbohydrate
No because no peptide fragment!
Celiac

49. What is the pathology seen in chronic transplant rejection?
isotype
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
A recomb cytokine of IL 2; RCC and metastatic melanoma
MHC class molecules bind to KIRS or CD94 to prevent killing

50. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
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
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Activate macrophages
Secretory component