Interest in and limitations of monoclonal anti-T-cell antibodies for the follow-up of renal transplant patients.

The OKT series of anti-T-cell monoclonals has been used on 442 occasions in 41 renal allograft recipients in a 6-12 month follow-up study. Standard immunosuppressive therapy (including antithymocyte globulin in 26 patients) tended to decrease the helper-inducer/suppressor-cytotoxic cell ratio (OKT4/OKT8). Conversely, 71% of 35 renal failure episodes were associated with increased OKT4/OKT8 ratios. Twenty-three percent of renal failure episodes were associated with dramatically decreased OKT4/OKT8 ratios. At least half of these cases could be explained by a cytomegalovirus infection. In fact, similar infections were found in 6 out of 17 patients with low OKT4/OKT8 values in the absence of renal failure. These results prompt us to use anti-T cell monoclonals for the diagnosis of rejection because only nine episodes of transient increase in the OKT4/OKT8 ratio were observed in the absence of rejection. The interest of this new method for the immunological follow-up of transplanted patients is, however, limited by the difficulty in interpreting a significant percentage of tests because of (1) the presence of doubly labeled cells (OKT4+OKT8+) or the significant discrepancy between the number of OKT3+ cells and total cells labeled with OKT4 and/or OKT8 antibodies; (2) gross lymphocytopenia--most often observed in patients receiving antithymocyte globulins plus steroids; and (3) the clinically unexplained shifts in the T cell subset ratios mentioned above.