The effect of lymphocytes from renal transplant patients on glomerular basement membrane sulfate uptake

We have studied the effect of peripheral blood mononuclear cells (PBMC) from renal transplant patients on³⁵sulfate uptake by rat glomerular basement membrane (GBM). Nine patients were included in the study; six were studied during an episode of acute allograft rejection and seven while not undergoing acute rejection. The sulfate uptake index, calculated as the ratio between uptake by GBM from rat glomeruli cocultured with PBMC and³⁵sulfate incorporation by GBM from glomeruli cultured alone, was significantly higher when glomeruli were co-cultured with PBMC from patients undergoing an acute rejection (3.26 ± 1.18, mean ± SEM) than it when glo meruli were cocultured with PBMC from nonrejecting transplant patients not showing proteinuria (0.81±0.11) (P = 0.0053). After reversing the acute allograft rejection with resolution of proteinuria, the sulfate uptake index returned to normal in four of five patients. The fifth patient had persistent nephrotic syndrome and his sulfate uptake index remained elevated. These findings are similar to those observed in idiopathic minimal lesion nephrotic syndrome patients in relapse. Because the GBM sulfated compounds may play a role in glomerular permeability to plasma proteins, by acting on these compounds PMBC may be a common mechanism for proteinuria.