Early prediction of acute homograft rejection: urinary assay for polyribosomal-rich lymphocytes.

Urinary cytology from 29 pediatric renal homograft recipients was evaluated for the presence of polyribosomal-rich (pyroninophilic) lymphocytes during an 8-month period. Seven episodes of acute (cell-mediated) rejection occurred in 21 cadaveric renal recipients. No episodes of rejection occurred during this period in the living-related recipients. Each episode of rejection was associated with significant polyribosomal-rich lymphocyturia 5 to 11 days before the onset of clinical rejection as diagnosed by conventional methodology. In addition, significant lymphocyturia occurred 1 to 3 days before and simultaneous with a sustained elevation in serum creatine. Falsely positive assays demonstrating occasional to 1 plus (less than 10 per cent) ribosomal-rich lymphocyturia occurred in 10 of 29 patients. None of these falsely positive-reacting patients demonstrated acute rejection. In our experience the urinary assay for polyribosomal-rich lymphocytes proved to be an early indicator of acute rejection. It is hoped that by early institution of antirejection therapy based on this parameter homograft rejection may be aborted or its severity diminished.