2-Immunopathology Flashcards
types of grafts
- autograft- own tissues
- isograft- id twin, same genetic background
- allograft- same species, diff genetics
- xenograft- diff species
cellular mechanisms rejection
type IV hypersensitivity
- cell med cytotoxicity- host cytotoxic lymphs destroy graft parenchymal and endo cells by releasing perforins and granzymes = apop
- delayed type - helper lymphs > cytokines = recruit mononuc cells, inflamm mediators, tissue damage
inflamm meds = TNF, INF-gamma, IL-2
destruction pathways transplants
kidney
- direct = APC in graft from donor, leads to CD8 damaging tenal tubule epi cells, endothelitis, activated macros
- indirect = APC of recipient, leads to act macros, Ab’s injury endo cells of renal blood vessels
humoral mechanism
target graft vasculature
1. Ab binds HLA moles in graft endo to act complement = acute inflamm, vasculitis like type II hypersens
2. Ag-Ab complexes fix complement = necrotize, immune complex vasculitis
hyperacute rejection
-recipient sensitized from prior transplants, transfusions, pregnancies
-immediate/within minutes
-complement act, vasculitis with fibrinoid necrosis, thormbosis, ischemia
avoid by cross matching recip serum with donor lymphs to find cytotoxic Ab
acute rejection
days/months post transplant/withdrawal of immunosupp theapy
-progress rapidly
-cellular + humoral + combo mechanisms
-tubular damage and endothelitis from CD9, extensive interstitial inflamm from CD4 cytokines
acute humoral rejection
anti-graft Ab deposit in graft vasculature
patterns= necrotizing vasculitis + intimal thickening from fibros, foamy macros, myocytes
chronic rejection
months-years after transplant
-humoral injury = prolif vascular lesions
-cellular injury- cytokine induced prolif of vascular SM + collagen in ECM
vascular changes + intersititial fibrosis + tubular atrophy + chronic inflamm
heart transplantations
for advanced irreversible myocardial disease + intractable congestive heart failure
-get myocyte necrosis and coronary artery disease from intimal prolif
-also silent MI’s leading to heart failure or sudden death bc no nerve innervation of SA node
cyclosporine
blocks nuclear factor of activated T cells
-transcription factor for IL-2 stim of T cells
hematopoietic cell transplants
for treating hematologic disorders, non hematologic malignancies, immunodefs
-stem cells from donor marrow or peripheral blood + stim by hematopoietic growth factors
graft versus host disease, infection, immunodef complications
graft vs host disease
cell mediated rxn where donor T cells recog host HLA antigens as foreign = type IV rxn
targets epi of skin, GI tract, liver
actue GVHD
days-weeks post engraftment via donor cytotoxic T cells/cytokines destroy epi cells
rashes, exfoliation, ulcerative gastroenteritis, bile duct necrosis, profound immunosuppr
chronic GVHD
with or without acute GVHD
-from autoreactive T cells from donor stem not clonally deleted bc minimal immune fxn
mimics systemic sclerosis bc fibrosis of dermis/skin appendages, GI mucosa, bile ducts, lungs
self antigen intracellular molecules
- double stranded DNA = SLE
- histones = SLE
- topoisomerase I = diffuse scleroderma
- centromere proteins = limited scleroderma
criteria for dx autoimmune disease
- immunologic rxn to a self Ag or native tissue
- rxn primary to pathogenesis not secondary to tissue damage
- no other well defined cause/etiology
triggers of autoimmune disease
- genetics- certain MHC alleles on D locus, esp PTPN-22 gene for protein tyrosine phosphatase
- microbes - cross reactivity, tissue damage, inc APC co stim moles, non specific B and T stimulation
- gender- higher in females, hormones?
mechanisms of autoimm
- fail of tolerance/immune reg
- fail of T cell anergy
- fail of apop of self reactive cells
- fail/dysfxn of reg CD4 T cells
- molecular mimicry
- polyclonal lymphs activation
- emergence of sequestered Ag
- exposure of cryptic antigenic determinants
ANA testing
uses human tissue cell culture nuclei aka Hep 2 for specificity of nucleus componenets targeted by Ab
-either pos or neg
-titers
-fluorescent staining
peripheral staining
aka rim staining
-Ab to double strand DNA
-SLE active flares
homogenous/diffuse staining
Ab to chromatin, double strand DNA, histones
-anti histone specfic to drug induced LE
RA and SLE
speckled staining
Ab to ribonucleoproteins and DNA topoisomerase
-sjogrens syndrome
-if small nuclear RNP particles then SLE
-topo = systemic sclerosis diffuse
centromere staining
Ab to centromeres
-limited scleroderma, systemic sclerosis
nucleolar staining
Ab to nucleolar RNA
-SLE, systemic sclerosis, limited scleroderma