Endocapillary glomerulitis in the renal allograft

Endocapillary glomerulitis is characterized by an increase in number of mononuclear cells in the glomerular capillary lumina. This lesion has been described in the early posttransplant period, but its pathogenesis, relation to conventional rejection, and prognostic impact is not well known. Using the definitions, scorings, and gradings of the Banff system for classification and grading of histopathologic changes in the renal allograft, we have analyzed 444 consecutive renal allograft biopsies from the first 90 days posttransplant. Moderate or severe glomerulitis occurred in 13.5% of the biopsies. There was a strong tendency toward clustering of glomerulitis: if one biopsy from a patient had glomerulitis, there was a high probability that it occurred in other biopsies from the same patient. There was some correlation with conventional acute rejection, but 40% of all biopsies with glomerulitis had no rejection and 53% of all biopsies with rejection had no glomerulitis. Graft function at biopsy was nil or decreased in many patients, but this could largely be explained by the independent presence of primary graft dysfunction or conventional rejection, these conditions being a frequent indication for performing a graft biopsy. Moderate or even severe glomerulitis was, however, compatible with a functioning graft. No correlation between glomerulitis and active CMV infection was found. The one-year graft survival of grafts with early posttransplant glomerulitis was 66%. If early conventional acute rejection is taken into consideration, graft survival does not seem to be influenced by the presence of glomerulitis. Early posttransplant endocapillary glomerulitis may be a peculiar pattern of rejection with a pathogenesis different from that of conventional rejection, but the present investigation does not demonstrate any adverse effects on graft function or graft prognosis.