Prognostic significance of T cell associated surface antigen density changes during OKT3 therapy of renal allograft rejection

We describe 12 acute rejection episodes in 11 cadaver donor renal allograft recipients who required OKT3 rescue treatment for steroid-resistant acute rejection (9) or for severe vascular (antibody-mediated) rejection (3). There were 3 treatment failures with subsequent graft loss. Using 2-color flow cytometry the total T (CD3), B (DR+), activated T (CD3DR), T helper/inducer (CD4), T cytotoxic/suppressor (CD8) and activated T cytotoxic cell (CD8DR) subsets were analyzed before, in mid course (5 to 7 days) and at the end of 12 to 14 days of therapy with 5 mg. OKT3 intravenously daily. In parallel changes in the density of such T cell associated antigens were analyzed. Significant decreases in the mean levels of the CD3 (p <0.001), CD3DR (p <0.05), CD4 (p <0.05), CD8 (p <0.05) and CD8DR (p <0.05) subsets were observed at mid course. A significant decrease in the density of CD3 was observed (p <0.0001). The surface antigen density of CD3DR, CD4 and CD8 had decreased by 160% (p <0.002), 383% (p <0.001) and 260% (p <0.001), respectively. At the end of treatment CD3 and CD4 subset levels increased by 425% and 240% (p <0.001 and p <0.005), respectively. In contrast, the CD3DR and CD8DR subset levels continued to decrease (p <0.05). A higher pre-treatment level of CD3DR and a less sharp decrease in CD3, CD4 and CD8 subsets were associated with a higher risk of treatment failure (p <0.05, p <0.01, p <0.05 and p <0.05, respectively). The mean decrease in the density of the CD3 marker in the lost grafts was significantly smaller compared to successful outcomes (p < 0.001). The results of this preliminary study suggest that OKT3 affects T cell associated antigens other than CD3. Such may provide a sensitive prognostic index for the effectiveness of OKT3 therapy, and permit the identification of those patients who might require higher doses and/or duration of OKT3 therapy to enhance renal allograft salvage rates.