Enumeration of Leu2a+, Leu2a+-DR+, and Leu2a+-Leu15+ cells in peripheral blood of renal transplant patients.

Immunological monitoring of peripheral blood cells of renal transplant patients may be helpful for diagnostic and prognostic purposes. We therefore enumerated the percentage of Leu2a+ cells as well as the occurrence of HLA-DR activation markers within this population. Since Leu2a+Leu15+ lymphocytes display suppressor functions in-vitro, this population was included in the study. Blood samples of 50 renal transplant patients within 3 months of transplantation and 41 pretransplant samples were investigated. As controls, peripheral blood cells from 10 healthy volunteers and 20 renal transplant patients with stable graft function more than 6 months after transplantation were examined. Just prior to transplantation the percentages of Leu2a+ cells, as well as the percentages of Leu15+ and DR+ cells within this population, varied considerably. Shortly after transplantation, clinical rejection episodes and cytomegalovirus (CMV) infections correlated with decreased percentages of Leu2a+ cells (P = 0.024 and 0.016, respectively). In nine patients with a decreased percentage of Leu2a+ cells shortly after transplantation but no rejection, the percentage of Leu2a+ cells normalized within 14 days. No correlation was found between increased percentages of Leu15+ or DR+ cells and rejection episodes, although the percentages of Leu2a+Leu15+ and Leu2a+DR+ cells increased significantly shortly before rejection (P less than 0.005). A decreased percentage of Leu2a+ cells, together with increased percentages of Leu15+ and DR+ cells, was seen in association with CMV infections (P less than 0.005). From this study we conclude that low percentages of Leu2a+ cells correlate with rejection episodes or CMV infections, whereas low percentages together with increased percentages of Leu2a+DR+ and Leu2a+Leu15+ cells are associated with CMV infections, especially in patients treated with high doses of cyclosporine.