title: Complement activation in acute humoral renal allograft rejection: diagnostic significance of C4d deposits in peritubular capillaries.
abstract: The distinction between acute humoral rejection (AHR) and acute cellular rejection (ACR) in renal allografts is therapeutically important, but pathologically difficult. Since AHR is probably mediated by antibodies to the donor endothelium that activate the classical complement pathway, it was hypothesized that peritubular capillary C4d deposition might distinguish this group. Renal biopsies (n = 16) from 10 patients with AHR who had acute graft dysfunction, neutrophils in peritubular capillaries, and a concurrent positive cross-match were stained for C4d by immunofluorescence. Control biopsies for comparison showed ACR (n = 14), cyclosporin A toxicity (n = 6), or no abnormality (n = 4). Peribiopsy sera were tested for anti-donor HLA antibody. C4d deposited prominently and diffusely in the peritubular capillaries in all AHR biopsies (16 of 16). IgM and/or C3 were also present in 19 and 44%, respectively. With two-color immunofluorescence, C4d was localized in basement membranes (type IV collagen+) and in the endothelium (Ulex europaeus agglutinin-I+). In ACR, no more than trace C4d was found in peritubular capillaries (P < 0.0001 versus AHR), and no patient had anti-donor HLA antibodies (0 of 8); 27% had neutrophils in peritubular capillaries. One of six biopsies with cyclosporin A toxicity had similar C4d deposits, and circulating anti-donor class I antibody was detected. Grafts with AHR were lost (40%) more often than those with ACR (0%; P < 0.02). C4d in peritubular capillary walls distinguishes AHR from ACR, is more specific and sensitive than traditional criteria, and is a potentially valuable adjunct in the diagnosis of graft dysfunction.
authors.affiliation: Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Collins
authors.forename: E E
authors.initials: EE
authors.lastname: Schneeberger
authors.forename: M A
authors.initials: MA
authors.lastname: Pascual
authors.forename: S L
authors.initials: SL
authors.lastname: Saidman
authors.forename: W W
authors.initials: WW
authors.lastname: Williams
authors.forename: N
authors.initials: N
authors.lastname: Tolkoff-Rubin
authors.forename: A B
authors.initials: AB
authors.lastname: Cosimi
authors.forename: R B
authors.initials: RB
authors.lastname: Colvin
mesh_terms: D000208:Acute Disease; D000917:Antibody Formation / Q000502:physiology; D001707:Biopsy, Needle; D015704:CD4 Antigens / Q000032:analysis*; D002196:Capillaries / Q000276:immunology; D003167:Complement Activation / Q000276:immunology*; D005260:Female; D006084:Graft Rejection / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular / Q000502:physiology; D007668:Kidney / Q000473:pathology*; D016030:Kidney Transplantation / Q000009:adverse effects / Q000276:immunology* / Q000473:pathology*; D007684:Kidney Tubules / Q000098:blood supply / Q000276:immunology; D008297:Male; D008856:Microscopy, Fluorescence; D012016:Reference Values
chemical_list: D015704:CD4 Antigens