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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.
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1. __________ are a part of the innate system.
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
pale central germinal centers
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
NK cells

2. How is the thymus organized? what happens in each section?
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
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
heavy chains

3. The MALT/GALT are not...
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
encapsulated
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
Tetanus - Botulinum - HBV - Rabies

4. where do NK cells develop?
The patient could become cyanotic in the OR!
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
Immunosuppression after kidney transplantation in combination with cyclosporine and corticosteroids
Not thymus - BM

5. Which antibodies can be multimeric?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
IgM and IgA
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions

6. All transplant rejections - _____________ are mediated by Type IV hypersensitivity
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
A chemotactic factor for neutrophils
except hyperacute
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

7. From where do cytokines come from?
Lymphocytes
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Anti U1 RNP (ribonucleoprotein)
Histamine; post capillary venules - vasodilation

8. What is the general structure of an Ab?
Superior mesenteric
TLR ad nuclear receptors
2 heavy chains and two light chains
acute phase reactants

9. What lymph node drains the anal canal (below the pectinate line)?
Anti IF
Superficial inguinal
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
Popliteal

10. in which immunodef order do you see a lot of pus? no pus?
A j chain
IgA
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

11. What is Aldesleukin? What is it used for
CD56
T
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
A recomb cytokine of IL 2; RCC and metastatic melanoma

12. What is passive immunity?
Paracortex
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Receiving preformed Antibodies
T cell activation; no with CD 4 or CD 8

13. 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)?
carboxy terminal
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
Paracortex; viral infection
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)

14. What are the autoantibodies for Celiac disease?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Antigliadin - antiendomysial (both are IgAs - anti tissue transgluataminase igA)
Superior mesenteric
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

15. which cytokine inhibits TH2 cells? secreted by who?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
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
Interferon gamma; Th1
IgM and IgG

16. Which HLA's are included in MHC I? MHC II?

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17. How is the antigen loaded onto a MHC II?
Interferon gamma; Th1
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
T cell dysfunction
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

18. What lymph node drains the scrotum?
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
IL 4 - 5 - 10 - 6
Superficial inguinal
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

19. What are superantigens? give two examples.
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
MHC I; from RER with help of the B2 microglobulin
Steroid responsive nephrotic syndrome
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

20. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
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
Anti viral and anti tumor
Acts as second signal on B cells to induce class switching to IgA; also stimulates eosinophils
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

21. describe the pathogenesis of delayed type IV hypersensitivity
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow
Immunosuppression after kidney transplantation

22. What is the toxicity of azathioprine?
Wiskott Aldrich syndrome
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Negative nitroblue tetrazolium reduction test
...

23. What happens in a secondary follicle?
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
mesenchymal
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

24. What are four results of a splenectomy?
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
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
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
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

25. Which are the only two antiinflammatory cytokines?
encapsulated
TGF beta and IL 10
T cell and antibody mediated vascular damage due to MHC non self being recognized as self by self lymphocytes and resulting in attack of the foreign antigens it presents (all of them); months to years after; no :(
Daclizumab; prevent ACUTE rejection of renal transplant

26. What is the symptoms involved in graft versus host disease? it What transplant cases does it usually occur? give an example
DM type I and RA
MHC class molecules bind to KIRS or CD94 to prevent killing
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
IgG

27. What bugs can actually infect the lymph node itself?
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization
A recomb cytokine of IL 2; RCC and metastatic melanoma
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
Activates Th1 helper cells; Macrophages

28. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
Anti SS- A (anti RO) and Anti SS- B
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Anti alpha subunit 3 of collagen on type IV bm
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP

29. What are the three types of APCs?
Th2; Th1
Sinusitis - otitis media - pneumonia
Macrophages - Dendritic cells - B cells
...

30. Describe the Mannose Lectin pathway
active complement pathway
Anti viral and anti tumor
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
IgM and IgD

31. How do endotoxin/LPS of gram negative bacteria stimulate the immune system if they do not have a peptide fragment?
Anti glutamate carboxylase and anti insulin
T cell precursor
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
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

32. What is recomb alpha interferon used for?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
pentamer
Antidesmoglein

33. What is the cause of thymic aplasia? What is its presentation? What are the labs?
Paracortex; viral infection
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
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
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

34. How do you test for type III hypersensitivity?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Immunoflourescent staining of tissue biopsies
Viral neutralization of igM and IgG!
Type IV

35. IgM can exist as a _______ also
B - T - and NK cells
Viral neutralization of igM and IgG!
pentamer
MHC II - B7

36. what bacteria are a splenectomy patient most susceptible to? why?
Negative selection
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
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
isotype

37. What is the monoclonal antibody to IL2 on activated T cells? What is it used for?
Daclizumab; prevent ACUTE rejection of renal transplant
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)
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
Delayed type hypersensitivity

38. What are the autoantibodies for polymyositis and dermatomyositis?
Pernicious Anemia and Hashimotos
Anti Jo -1
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
Inferior mesenteric

39. after C3 spontaneously hydrolyzes to C3b and C3a - what happens to C3a?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Increases expression of MHC I and MHC II and also activates NK cells
cannot cross placenta

40. How does igA cross the epithelium?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Anti TSh receptor
By transcytosis
Receiving preformed Antibodies

41. What are the cell surface proteins on NK cells?
MS - hay fever - SLE - goodpastures
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
MHC I - CD16 - CD56
Fc

42. What does granzyme do? who secretes it?
IgG
DM type I
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
Its a serine protease that activates apoptosis; NK and CD8

43. What happens in a deficiency of C3?
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
DM type I
lowest concentration
Negative!

44. What are the autoantibodies for sjorgens syndrome?
Anti SS- A (anti RO) and Anti SS- B
IgM
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Not thymus - BM

45. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
CD21 on B cells (although there is T cell lymphocytosis in EBV)
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

46. What are the autoantibodies for myasthenia gravis?
Anti Ach receptor
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
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
type four

47. What are the PALS?
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
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
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

48. Which disease is associated withB B27?
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Inferior mesenteric
Psoriasis - Ankylosis Spondylitis - IBD - Reiters; all seronegative spondylopathies
IL 4 - 5 - 10 - 6

49. What links the adaptive and innate immunity?
pale central germinal centers
The patient could become cyanotic in the OR!
Complement activation (active in both)
secondary

50. What are the autoantibodies for goodpastures syndrome?
IL 15; IL 12 - interferon Beta and interferon alpha
Anti alpha subunit 3 of collagen on type IV bm
Superficial inguinal
IgE; by activating eosinophils