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Immunology ` Immunology—Immune reSponSeS Immunology ` Immunology—Immune reSponSeS SECTIon II 119

Transplant rejection
type oF reJectIon onSet pathogeneSIS FeatureS
Hyperacute Within minutes Pre-existing recipient antibodies Widespread thrombosis of graft
A react to donor antigen (type II vessels (arrows within glomerulus A)
hypersensitivity reaction), activate Ž ischemia/necrosis
complement Graft must be removed

Acute Weeks to months Cellular: CD8+ T cells and/ Vasculitis of graft vessels with dense
B or CD4+ T cells activated interstitial lymphocytic infiltrate B
against donor MHCs (type IV Prevent/reverse with
hypersensitivity reaction) immunosuppressants
Humoral: similar to hyperacute,
except antibodies develop after
transplant

Chronic Months to years CD4+ T cells respond to recipient Recipient T cells react and
C APCs presenting donor peptides, secrete cytokines Ž proliferation
including allogeneic MHC of vascular smooth muscle,
Both cellular and humoral parenchymal atrophy, interstitial
components (type II and IV fibrosis
hypersensitivity reactions) Dominated by arteriosclerosis C
Organ-specific examples:
ƒ Chronic allograft nephropathy
ƒ Bronchiolitis obliterans
ƒ Accelerated atherosclerosis
(heart)
ƒ Vanishing bile duct syndrome
Graft-versus-host Varies Grafted immunocompetent Maculopapular rash, jaundice,
disease T cells proliferate in the diarrhea, hepatosplenomegaly
immunocompromised host and Usually in bone marrow and liver
reject host cells with “foreign” transplants (rich in lymphocytes)
proteins Ž severe organ Potentially beneficial in bone
dysfunction marrow transplant for leukemia
Type IV hypersensitivity reaction (graft-versus-tumor effect)
For immunocompromised patients,
irradiate blood products prior to
transfusion to prevent GVHD

FAS1_2019_02-Immunology.indd 119 11/7/19 3:24 PM