USMLE step 1 - immunology
Terms in this set (100)
what type of hypersensitivity reaction is graft-vs-host disease
presentation of graft-vs-host disease
diarrhea, hepatomegaly, jaundice, erythematous maculopapular rash
tetany, viral and fungal infections, congenital heart and great vessel defects (syndrome, mutation)
DiGeorge syndrome, 22q11 mutation
diarrhea, ear infections, pneumocystis pneumonia, oral candidiasis
causes of SCID
1) IL-2 receptor defect
2) adenosine deaminase deficiency (decreased DNA synth --> decreased B and T synth, apoptosis of rapidly proliferating cells)
3) MHC II deficiency
mechanism of myasthenia gravis
type II hypersensitivity reaction: IgG and IgM against acetylcholine receptors at neuromuscular junction
ptosis, diplopia, general weakness, thymus abnormalities
diagnosis of myasthenia gravis
EMG will show decremental response
edrophonium challenge will reverse symptoms
components of Th cell activation
1) phagocytosis and antigen presentation
2) MHCII/TCR-CD4 interaction
3) B27/CD28 co-stimulation
components of cytotoxic T cell activation
1) presentation of self or viral antigen
2) MHCI/TCR-CD8 interaction
3) Th1 secrete IL2 which activates cytotoxic T cell killing
components of B cell activation
1) Th differentiation to Th2, which secretes IL-4, 5, 6
2) Th2-CD40L/CD40 interaction
3) Th2-CD28/B7 interaction
defect in B cell maturation to plasma cells
common variable immune deficiency
sinopulmonary infections, autoimmune disease, lymphomas, young adult
common variable immune deficieincy
high IgA and IgE, low IgM
progressive deletion of B and T cells
molecules expressed by vascular endothelial cells that assist in rollin stage of leukocyte extravasation
molecule expressed by leukocytes that assist in rollin stage of leukocyte extravasation
molecule expressed by leukocyte that assists in tight-binding stage of leukocyte extravasation
molecule expressed by vascular endothelial cells that assists in tight-binding stage of leukocyte extravasation
molecules expressed by leukocytes and vasculature/stroma that assist in diapedesis (movement of leukocyte between endothelial cells to exit vessel)
type IV hypersensitivity reaction
negative nitroblue tetrazolium reaction
chronic granulomatous disease
manifestations of lupus anticoagulant
prolonged PTT with normal bleeding time
false positive VDRL
antiphospholipid antibody syndrome (thromboembolism, miscarriage)
C1 esterase inhibitor deficiency
hereditary angioedema (ACE inhibitors contraindicated)
sinus and respiratory tract infections
susceptibility to type III hypersensitivity reactions (serum sickness, arthrus reaction, post-strep glomerulonephritis, etc.)
recurrent neisseria infections
decay-accelerating factor deficiency
paroxysmal nocturnal hemoglobinuria
recurrent bacterial infections, no pus formation, delayed separation of umbilicus
leukocyte adhesion deficiency (LFA-1 defect)
recurrent staph and strep infections, partial albinism, peripheral neuropathy
chediak-higashi (microtubule dysfunction in phagosome-lysosome fusion)
recurrent infection with staph, pseudomonas, aspergillus, candida, e. coli
chronic granulomatous disease (NADPH oxidase deficiency)
fever, urticaria, arthralgia, glomerulonephritis, lymphadenopathy, vasculitis with fibrinoid necrosis and neutrophil infiltrate, hypocomplementemia
serum sickness (type III hypersensitivity reaction to drug, e.g. sulfonamides)
what cytokine suppresses Th1 cells?
what cytokine suppresses Th2 cells?
anti-DNA topoisomerase antibodies
primary biilary cirrhosis
anti-U1 ribonucleoprotein antibodies
mixed CT diesease
anti-smooth muscle antibodies
anti-glutamate carboxylase antibodies
diabetes mellitus type I
which immunoglobins activate classic complement pathway?
which immunoglobins can neutralize bacterial toxins and viruses?
which immunoglobin can cross the placenta?
which immunoglobin can cross epithelial cells by transcytosis
which immunoglobin can trap free antigens out of tissue while the humoral response evolves ?
which immunoglobin mediates type I hypersensitivity?
which immunoglobin activates eosinophils in response to worm infections?
where does MHC restriction and negative selection of T cells occur?
corticomedullary junction of the thymus
what are Langerhans giant cells?
collections of macrophages with nuclei arranged in a horseshoe or ring pattern in a caseating granuloma (e.g. M. tuberculosis infection)
how are macrophages activated?
by IFN-gamma, produced by Th1 cells
sinopulmonary infections, giardia, anaphylaxis on exposure to blood pruducts
sinopulmonary infections, beginning at ~6 months
Bruton's agammaglobulinemia (tyrosine kinase mutation prevents pre B cells from becoming mature plasma cells)
low Ig, thymic hypoplasia, elevated alpha-fetoprotein
ataxia telangiectasia (mutation in DNA repair enzyme that binds non-homologous ends)
what cytokine induces eosinophils?
what cytokine induces IgE?
what cytokine induces IgA
what cytokine promotes Th-->Th2 differentiation?
what cytokine both activates and is secreted by Th2?
what cytokine is important for macrophage recruitment?
what cytokine promotes Th-->Th1 differentiation?
Encapsulated bacterial infections, absent thymic shadow, live vaccine contraindicated.
bruton's agammaglobulinemia: Tyrosine kinase deficiency blocks pro- to pre-B cell maturation --> opsonization defect due to low Igs of all types
Severe pyogenic infections early in life.
hyper-IgM syndrome: CD40L defect on helper T cells --> class switching defect. High IgM, low all other Ig.
Sinopulmonary infections, milk allergies, diarrhea, anaphylaxis on exposure to blood products with deficient agent.
selective IgA deficiency: defect in isotype switching/failure to mature into plasma cells --> deficiency in particular Ig (most often IgA).
Increased risk of sinopulmonary infections, autoimmune disease, lymphoma. Can be acquired in 20s-30s.
common variable immunodeficiency: defect in B cell maturation --> decreased plasma cells and immunoglobulin.
Hypocalcemia/tetany, recurrent viral and fungal infections, absent thymic shadow, congenital heart and great vessel defects.
DiGeorge syndrome: 22q11 deletion, failure of 3rd and 4th pharyngeal pouches to develop.
IL-12 receptor deficiency
decreased Th1 response --> decreased IFN-gamma, disseminated mycobacterial infections
Coarse facies, non-inflammed staph abscesses, retained primary teeth, eczema, elevated IgE
Job's syndrome: Th cells fail to produce IFN-gamma --> inability of neutrophils to respond to chemotactic stimuli.
sinopulmonary infections, giardia, anaphylaxis when exposed ti blood products containing deficient element
N/V/D, ulcerations, syncope, flushing, tachycardia, bronchospasm, pruritis
mastocytosis (mast cell proliferation in bone marrow, intestine, etc, leading to inc histamine release)
occlusion of graft vessels, causing ischemia and necrosis within minutes of transplant
hyperacute transplant rejection: type II hypersensitivity reaction where RECIPIENT PRE-FORMED ANTIBODIES attack donor cells
vasculitis of graft vessels with dense interstitial infiltrate, within weeks of transplant
acute transplant rejection: RECIPIENT CYTOTOXIC T CELLS react to donor MHCs, reversible with immunosuppressants
obliterative vascular fibrosis, months to years after transplant
chronic transplant rejection:RECIPIENT CYTOTOXIC T CELLS AND ANTIBODIES react to donor MHC-I as if they were self MHC-I + agn, irreversible
rash, jaundice, hepatosplenomegaly, diarrhea, any time after transplant
graft vs. host disease: type IV hypersensitivity reaction where DONOR T CELLS attack recipient cells, causing severe organ dysfunction (may be beneficial in bone marrow transplant)
source, function of interferon alpha and beta
source: leukocytes, fibroblasts
function: inhibits viral protein synthesis by acting on uninfected cells
source, function of interferon-gamma
source: Th1, cytotoxic T cells, NK cells
function: stimulate cell-mediated immunity, inhibit Th2, increased expression of class I and II MHC
what type of immunity is TNF involved in?
atypical cells with abundant lacy cytoplasm in peripheral blood smear
activated T cells
positive selection of T cells (where, what)
thymic cortex; T cells expressing receptors capable of binding surface self MHCs survive
negative selection of T cells (where, what)
thymus corticomedullary junction; T cells expressing receptors with high affinity for self antigens undergo apoptosis
Th1 --> IFN-gamma --> macrophages --> TNF-alpha -- granuloma formation and maintenance
disseminated mycobacterium infections, dec IFN-gamma
IL-12 receptor deficiency (dec Th1 response)
etiology of rheumatic fever/heart disease
type II hypersensitivity reaction mediated by antibodies to M protein (group A strep)
cause of death in rheumatic fever/heart disease
HLA types associated with MHC I
HLA-A, B, C
HLA types associated with MHC II
HLA-DR, DP, DQ
psoriatic arthritis, ankylosing spondylitis, inflammatory bowel disease, reactive arthritis
MS, SLE, Goodpasture's, hay fever
DM type 1
DM type 1, RA
pernicious anemia, Hashimoto's
steroid responsive nephrotic syndrome
what type of cell produces perforin and granzymes?
NK cells (only lymphocyte of innate immunity)
what is response to a cell that does not express any MHC-I?
NK cell-mediated induction of apoptosis
recurrent sinusitis, bronchiectasis, infertility, situs inversus
Kartegener's syndrome (dynein arm defect --> immotile cilia)
beta-2 microglobulin is a component of what?
class I MHC
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