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. 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?
delayed!
Thrombocytopenia
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
IgE; by activating eosinophils

2. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
Fab portion
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)
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

3. What is the pathogenesis of a hypersensitivity reaction?
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Paracortex; viral infection
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
Pernicious Anemia and Hashimotos

4. IgE has the ___________ in the serum
Superficial inguinal
Paracortex; viral infection
lowest concentration
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

5. The two heavy chains of an antibody contribute to the...
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
Axillary
Fab portion
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)

6. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
DM type I and RA
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Glycoproteins; HLA
CD21 on B cells (although there is T cell lymphocytosis in EBV)

7. what secretes IL 4?
Yes
Bind FcG for antibody dependent cellular cytotoxicity
Basophils! THey want IG E class switch!
Edema and necrosis in that region

8. Which antibodies can be multimeric?
IgA
IgM and IgA
...
IL 1 and IL 6

9. What is the main function of interferons?
IgG
Edema and necrosis in that region
Anti glutamate carboxylase and anti insulin
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)

10. Which is the main antibody that provides passive immunity to infants?
IgG
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Th2; Th1
Histamine; post capillary venules - vasodilation

11. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
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 BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
A - B - C; all the D's

12. What does granulysin do?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
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
...
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

13. Describe the capsular structure of a lymph node; What are the functions of the LN?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
False! B cell class switching requires a second signal
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
IL 5

14. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
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
T cell dysfunction
Anti U1 RNP (ribonucleoprotein)
Cross link

15. What are the T cell functions?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Activate macrophages
Anti U1 RNP (ribonucleoprotein)
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection

16. What is the defect in Leukocyte adhesion defect? What is the presentation? What are the labs?
DM type I and RA
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
Activate macrophages
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

17. What is colostrum?
type four
lowest concentration
Sinusitis - otitis media - pneumonia
The igA found in breast milk

18. So antibodies are the effectors for the humoral response. List some of their functions.
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
NK cells
CD56
Activates cytotoxic CD 8 T cells as second signal

19. What is an autograft? syngeneic graft? allograft? xenograft? What is an ex of an allograft? xenograft?
CD21 on B cells (although there is T cell lymphocytosis in EBV)
pale central germinal centers
cannot cross placenta
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve

20. What is thrombopoietin used for?
Thrombocytopenia
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
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
MHC I - CD16 - CD56

21. What is the mode of inheritance of Chediak Higashi syndrome? What is the disease d/t? What does it result in? What is the presentation?
neutrophilia!
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
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
Fc

22. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Influenza; antigenic shift; antigenic drift
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
IgG
Anti glutamate carboxylase and anti insulin

23. What is the common variable immunodeficiency ? How is it different from Brutons?
IL 1 and IL 6
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Liver! (they are proteins circulating in the blood)
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

24. Which disease is associated with B8?
type four
Carbohydrate
Basophils! THey want IG E class switch!
Graves

25. What is the toxicity of muromonab?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Acts as second signal on B cells to induce class switching to IgE and IgG
Fab portion

26. What does interferon gamma do? What two type of cells does it attack mostly?
Stimulate the liver to release acute phase reactants
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7

27. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
Axillary
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
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

28. In thymic development - What is the positive selection? negative selections?
When you select for which MHC it will have; take out the lymphs that self react
T
T cell dysfunction
Hemochromatosis

29. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
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
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
CD21 on B cells (although there is T cell lymphocytosis in EBV)
Negative nitroblue tetrazolium reduction test

30. What part of the complement system also acts as an opsonin? What is opsonization? can you Name two other opsonins?
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
Superficial inguinal
IgM and IgG

31. what results in symptoms of shock in an acute hemolytic transfusion reaction?
Since it is a comp dependent type II hypersensitivity reaction; C3a brings anaphylotoxins that bring in mediators of shock
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
Axillary
Active; passive - fast but short half life (3 weeks!)

32. What cytokines are released by Th1 cells?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Tetanus - Botulinum - HBV - Rabies
IgM and IgD
Interferon gamma and IL 2

33. hat is the presentation of Jobs syndrome or Hyper IgE?
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
2 heavy chains and two light chains
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith

34. What are the autoantibodies for type I diabetes mellitus?
Anti glutamate carboxylase and anti insulin
MHC I - CD16 - CD56
CD56
Cells that stil have weird parts of their membrane that macrophages usually bite off

35. in which immunodef order do you see a lot of pus? no pus?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
type four
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

36. 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?
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
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

37. What lymph node drains the sigmoid colon?
Pernicious Anemia and Hashimotos
Th cells fail to produce interferon gamma; a lot of IgE
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Inferior mesenteric

38. what cell surface marker is used for NK cells as it is unique to them?
Superior mesenteric
CD56
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

39. Give an example of someone who could get hyperacute transplant rejection.
Previous transfusion; pregnant woman whose fetus had paternal antigens
Cells that stil have weird parts of their membrane that macrophages usually bite off
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
MS

40. What are the mediators that mast cells release?
Anti viral and anti tumor
When you select for which MHC it will have; take out the lymphs that self react
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)

41. What are the three types of lymphocytes?
IgM and IgD
By transcytosis
IgG
B - T - and NK cells

42. What do macrophages secrete that activate Th1 cells to secrete interferon gamma?
TNF alpha and IL1
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Alternative splicing of mRNA
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

43. Which TCR MHC system is important for viral immunity? neoplastic? donor graft cells?
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!
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
All MHC 1/CD8
IL 4 - 5 - 10 - 6

44. What is recomb gamma interferon used for?
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
Chronic granulomatous disease
encapsulated
Barrel hoop basement membrane fenestrations

45. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
Ischemia and necrosis of graft due to occlusion of vessels and fibrinoid necrosis and thrombosis within the vessels
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)

46. What is the mechanism for sirolimus? what else it known as?
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
A chemotactic factor for neutrophils
Hereditary angioedema; PNH
Cytokine IL 10 secreted by Th2

47. Which disease is associated with DR7?
DAF and C1 esterase inhibitor on cells prevent complement activation on their surfaces (microbial surfaces lack this)
Hereditary angioedema; PNH
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Steroid responsive nephrotic syndrome

48. What is MHC II made out of? Where is it found? What does it bind to? What type of antigens does it present?
Popliteal
TLR ad nuclear receptors
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp

49. What can cause a lymph node enlargement?
DM type I
Local infection/inflammation; infection of the ln itself; metastasis
IL 1 and IL 6
IgAs in mothers breast milk!

50. What are the cell surface proteins on NK cells?
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
MHC I - CD16 - CD56
IgAs in mothers breast milk!
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP