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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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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. Leukocyte adhesion defect presents with...
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 :(
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
neutrophilia!
IgM

2. What are the cell surface proteins for Macrophages? which two are for opsonins?
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
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
DM type I

3. What does IgA pick up from epithelial cells before being secreted?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Secretory component
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
IgM and IgG

4. What is the two fates of the RBCs that go through the spleen? what happens eventually to all of them>
A j chain
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
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
not Ab mediated

5. What is the defect in hyper IgM syndrome? What are the lab results?
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
TLR ad nuclear receptors
Cross link
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

6. What are the autoantibodies for hashimotos?
Antihistone
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
MHC I - CD16 - CD56
Antimicrosomal and antithyroglobulin

7. What are the autoantibodies for myasthenia gravis?
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
Anti Ach receptor
Hemochromatosis
Edema and necrosis in that region

8. What is the most common example of passive immunity?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
IgAs in mothers breast milk!
Thrombocytopenia
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE

9. What are the autoantibodies for systemic sclerosis?
Anti topoisomerase
Anti alpha subunit 3 of collagen on type IV bm
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
TLR ad nuclear receptors

10. What is the thymus ? Where is it located? is it encapsulated? How many lobes does it have?
2 heavy chains and two light chains
IL 15; IL 12 - interferon Beta and interferon alpha
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
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

11. 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?
Negative selection
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Superficial inguinal
Delayed type hypersensitivity

12. What is the clinical use of Muromonab?
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
Immunosuppression after kidney transplantation
Pernicious Anemia and Hashimotos

13. What is hereditary angioedema? What are the C3 levels?
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
CRP - C3b - IgM
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
IgG

14. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
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
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
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

15. What are the autoantibodies for drug induced lupus?
Antihistone
IgE
Hemochromatosis
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

16. What is the main cytokine that activates eosinophils?
IL 4
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
IL 4 - 5 - 10 - 6
IL 5

17. What does IL 10 do? who is secreted by?
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
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
Basophils! THey want IG E class switch!
Paracortex

18. Name 5 ways Antibody diversity is generated?
Secretory component
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
isotype
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive

19. what else does interferon gamma do other than inducing ribonuclease production - activating NK cells - inducing increased MHC expression?
Liver! (they are proteins circulating in the blood)
Activate macrophages
Axillary
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells

20. other than mediating shock - what else does TNF alpha do? who releases it mainly?
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
Activates Th1 helper cells; Macrophages
except hyperacute
Not thymus - BM

21. describe the pathogenesis of delayed type IV hypersensitivity
Anti glutamate carboxylase and anti insulin
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
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Th1; interferon gamma; IL 2 for cytotoxic T cell activation

22. other than C3a - what other complement acts as an anaphyloxin?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
C5a
Anti IF
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells

23. T/F B cells do not require a second signal
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
False! B cell class switching requires a second signal
Anti U1 RNP (ribonucleoprotein)
Chronic granulomatous disease

24. What is immune complex disease? give an example.
Type III hypersensitivity where an internal antigen antibody complexes activate classical complement pathway resulting in C3a neutrophilic chemotaxis and neutrophilic lysosomal death. SLE
No because no peptide fragment!
Th2; Th1
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

25. What lymph node drains the lateral side of the dorsum of the foot?
Popliteal
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
IL 4

26. What does IgE do on the surface of the mast cell to induce inflammatory mediator release?
Cross link
Activate macrophages
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
IgG

27. What are the two signals required for B cell class switching? Which is the second signal?
RNA segment reassortment
Paracortex; viral infection
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
IgE

28. what happens in a deficiency of C5- C8? why dont you get recurrent pyogenic infections like in C3 def?
Anti alpha subunit 3 of collagen on type IV bm
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
Superficial inguinal

29. 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?
AR; defect in MT function results in decreased transport and phagocytosis; recurrent pyogenic infections by staphylococci and streptococci - partial albinism - and peripheral neuropathy
pentamer
Anti Ach receptor
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

30. What does it mean if there are igM in the serum at birth?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Cytokine IL 10 secreted by Th2

31. What kinds of receptors activate innate immunity?
Antiviral by inducing ribonuclease which degrades only viral mRNA (prevents protein synthesis) and activates NK cells to kill virus infected cells
Yes
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
TLR ad nuclear receptors

32. What are the autoantibodies for pemphigus bulgaris?
Antidesmoglein
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
IgA
Complement activation (active in both)

33. What is the antimetabolite precursor of 6 mercaptopurine? What is the result?
...
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
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
Alternative splicing of mRNA

34. In thymic development - What is the positive selection? negative selections?
Chronic granulomatous disease
CD56
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
When you select for which MHC it will have; take out the lymphs that self react

35. Monomer in circulation - ___ when secreted
lowest concentration
dimer
Internal iliac
S. aureus - E. Coli - aspergillus

36. which B and T cell disorder presents with specifically low IgM?
T cells react to the angtigen and activate leukocyted (macrophage acitivation)
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Wiskott Aldrich syndrome

37. Which disease is associated with DR7?
MHC I - CD16 - CD56
Immunosuppression after kidney transplantation
Delayed type hypersensitivity
Steroid responsive nephrotic syndrome

38. What is filgrastim and sargramostim? and What is it used for?
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Anti Ach receptor
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
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

39. What are four results of a splenectomy?
Superficial inguinal
Humoral
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis
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

40. What is the main function of TNF alpha? How does it do this?
Graves
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
IgAs in mothers breast milk!

41. Which antibodies can be multimeric?
No because no peptide fragment!
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
IgM and IgA
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

42. What is recomb alpha interferon used for?
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
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
A chemotactic factor for neutrophils
Activate macrophages

43. What is epo used for?
Anemias (esp due to renal failure)
Internal iliac
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Sinusitis - otitis media - pneumonia

44. where do NK cells develop?
IL 5
DM type I and RA
Not thymus - BM
Antidesmoglein

45. What is MHC I made out of? Where is it found? What does it bind to? What type of antigens does it present?
RNA segment reassortment
An alpha chain and a B2 microglobulin; on all nucleated cells; TCR and CD8; intracellular antigens
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Activates Th1 helper cells; Macrophages

46. describe the classic complement pathway.
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
T cell dysfunction

47. Which MHC presents intracellular peptides? how so?
MHC I; from RER with help of the B2 microglobulin
T
Paracortex
Opsonization (Brutons agammaglobulinemia) - adhesion (Leukocyte adhesion defect) - phagocytosis (chediak higashi syndrome) - respiratory burst (chronic granulomatous disease)

48. So antibodies are the effectors for the humoral response. List some of their functions.
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Anticentromere; anti Scl -70 (anti DNA topoisomerase I)
Cross link antigens which increases their phagocytability; activate complement for MAC attack; opsonization; neutralization

49. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
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
IL 15; IL 12 - interferon Beta and interferon alpha
The igA found in breast milk

50. What are the autoantibodies for goodpastures syndrome?
Previous transfusion; pregnant woman whose fetus had paternal antigens
Anti alpha subunit 3 of collagen on type IV bm
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
A recomb cytokine of IL 2; RCC and metastatic melanoma