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. What are complements in the complement system? What activates them? there seems to be different ones - What are these pathways called?
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
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

2. The Fc region is found on the...
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Its a serine protease that activates apoptosis; NK and CD8
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
carboxy terminal

3. What are the autoantibodies for primary biliary cirrhosis?
Anti mitochondrial
IL 5
TLR ad nuclear receptors
Anti Ach receptor

4. can igG cross the placenta?
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
Yes

5. ________ regulate the cell mediated response.
Humoral
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
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Legionella - N. gonorrhea - L. monocytogenes - viruses - protozoa (leismaniasis)

6. What are the autoantibodies for Celiac disease?
Anti TSh receptor
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
Activates cytotoxic CD 8 T cells as second signal
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)

7. How is the thymus organized? what happens in each section?
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
Bind FcG for antibody dependent cellular cytotoxicity
Delayed type hypersensitivity
Viral neutralization of igM and IgG!

8. The ______ in the BM are DN - the DP are in the cortex of thymus
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
S. aureus - E. Coli - aspergillus
T cell precursor
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)

9. What is chronic mucocutaneous candidiasis d/t?
T cell dysfunction
IgG
A chemotactic factor for neutrophils
T cell precursor

10. The pathogenesis of contact dermatitis is ________ hypersensitivity
T cell dysfunction
type four
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
dimer

11. Type IV hypersensitivity is i...
not Ab mediated
IL 4 - 5 - 10 - 6
Axillary
pentamer

12. in which immunodef order do you see a lot of pus? no pus?
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
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
pale central germinal centers
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis

13. What lymph node drains the sigmoid colon?
If there is class switching and plasma cell production (that is when memory cells are produced)
Inferior mesenteric
Antimicrosomal and antithyroglobulin
IgG

14. Which diseases are associated with DR4?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Negative!
DM type I and RA
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

15. What lymph node drains the rectum (above the pectinate line)?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
Fc
CD56
Internal iliac

16. What links the adaptive and innate immunity?
Receiving preformed Antibodies
Acts as second signal on B cells to induce class switching to IgE and IgG
C5a
Complement activation (active in both)

17. What lymph node drains the duodenum - jejunum?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Superior mesenteric
Carbohydrate
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

18. What lymph node drains the upper limb?
pentamer
2 heavy chains and two light chains
Axillary
CRP - C3b - IgM

19. What does CD16 on NK cells do?
DM type I
TNF alpha and IL1
No because no peptide fragment!
Bind FcG for antibody dependent cellular cytotoxicity

20. What is the presentation of scid? treatment?
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Axillary
MHC I; from RER with help of the B2 microglobulin

21. describe the classic complement pathway.
Rheumatic arthritis
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
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
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

22. What is the pathogenesis of HyperIgE syndrome? What are the labs?
Interferon gamma; Th1
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Th cells fail to produce interferon gamma; a lot of IgE
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein

23. What is the general structure of an Ab?
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
MHC I/CD8 and IL2/IL 2 Receptor (IL 2 is from Th1!); cytoxicity!
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
2 heavy chains and two light chains

24. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Tetanus - Botulinum - HBV - Rabies
Influenza; antigenic shift; antigenic drift
The patient could become cyanotic in the OR!
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies

25. What happens in a deficiency of C3?
IgM and IgG
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Hereditary angioedema; PNH
type four

26. 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?
Severe pyogenic infections early in life
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
Para aortic
Superior mesenteric

27. What lymph node drains the stomach?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Cross link
Celiac
Interferon gamma; Th1

28. what characterizes an arthus reaction?
Edema and necrosis in that region
RNA segment reassortment
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
lowest concentration

29. What are the autoantibodies for goodpastures syndrome?
Anti TSh receptor
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
Wiskott Aldrich syndrome
Anti alpha subunit 3 of collagen on type IV bm

30. What can cause a lymph node enlargement?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Local infection/inflammation; infection of the ln itself; metastasis
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
TLR ad nuclear receptors

31. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
Barrel hoop basement membrane fenestrations
Anti SS- A (anti RO) and Anti SS- B
By transcytosis
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells

32. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
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
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction

33. Which antibody mediates immunity to worms? how?
IgE; by activating eosinophils
mesenchymal
IgM
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

34. which of the hypersensitivity reactions is not Ab mediated?
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
carboxy terminal
Type IV
Local infection/inflammation; infection of the ln itself; metastasis

35. What are HEV? Where are they found? Where does the vasculature of the lymph node travel to?
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Antimicrosomal and antithyroglobulin
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 glutamate carboxylase and anti insulin

36. What does Interferon alpha and beta do? how?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
TGF beta and IL 10
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

37. Which helper T cells' development is induced by IL 4? IL 12?
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
Th2; Th1
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L

38. Which diseases are associated with DR5?
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
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
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
Pernicious Anemia and Hashimotos

39. What type of side chains are found on Fc region of an antibody?
Carbohydrate
Negative selection
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Antidesmoglein

40. What is serum sickness? give an example.
Bind FcG for antibody dependent cellular cytotoxicity
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
Local infection/inflammation; infection of the ln itself; metastasis
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

41. which cytokine inhibits TH2 cells? secreted by who?
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Interferon gamma; Th1
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)
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

42. IgG...
Antihistone
CD21 on B cells (although there is T cell lymphocytosis in EBV)
opsonizes
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

43. What lymph node drains the anal canal (below the pectinate line)?
Superficial inguinal
DM type I and RA
Viral neutralization of igM and IgG!
isotype

44. What are MHC Class molecules (ie what macromolecule are they made out of)? what gene are responsible for MHC?
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Glycoproteins; HLA
Ig - CD19 - CD20 - CD21 - CD40 - MHC II - B7
False! B cell class switching requires a second signal

45. How does igA cross the epithelium?
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
Edema and necrosis in that region
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
By transcytosis

46. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

47. Which is the most abundant antibody in blood?
Axillary
Macrophages - Dendritic cells - B cells
Celiac
IgG

48. The lymphocytes are ________ origin
Hemochromatosis
mesenchymal
Carbohydrate
NK cells

49. What is the common variable immunodeficiency ? How is it different from Brutons?
Anti IF
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
Influenza; antigenic shift; antigenic drift
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

50. What does granulysin do?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Complement activation (active in both)
Antimicrobial also secreted by CD8 and NK cells that induces apoptsosis
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells