Serial flow cytometric analysis of T-cell surface markers can be useful in differential diagnosis of renal allograft dysfunction.

We examined changes in the circulating T-cell subsets and their activation to see if consistent changes occur following renal transplantation, during acute rejection episodes (ARE), cytomegalovirus (CMV) infection, and cyclosporine (CsA) nephrotoxicity. Serial blood samples were taken from 28 patients on standard triple immunosuppresion therapy. Using two-colour flow cytometric analysis, the percentages of CD3+, CD4+, and CD8+ T-cells were determined, and coexpression of CD25, HLA/DR, and CD45 isoforms used to define their activation status. During ARE and CMV infection, increased levels of circulating CD4+ CD25+, CD8+ HLA/DR+, CD4+ CD45RO+, CD8+ CD45RO+ were observed. The increased levels of CD45RO+ T-cells were associated with a significant decrease in the percentages of CD45RA+ of both CD4+ and CD8+ T-cells. No significant changes were seen during CsA nephrotoxicity. The pattern of marker expression seen during ARE and CMV infection was similar to that seen in Con-A stimulated T-lymphocytes from 22 normal controls. We conclude that, the increase in the levels of these surface markers do not differentiate between lymphocyte activation indicative of rejection or infection, but clearly distinguish episodes of CsA nephrotoxicity. These results could be useful in the differential diagnosis of renal allograft dysfunction.