The effects of immunomodulation on peripheral T cell subsets.

Monoclonal antibody assays were employed to monitor modifications induced in human peripheral lymphocyte subsets by thymectomy or the administration of a series of immunomodulating drugs: synthetic thymic factor, cimetidine or various combinations of anti-thymocyte globulin, azathioprine and steroids. In patients with myasthenia gravis, thymectomy produced a gradual progressive decrease in the elevated OKT4/OKT8 ratios associated with this disease until normal ratios were achieved after one year. Administration of synthetic thymic factor to three immunodeficient children for one month produced increased serum IgA levels accompanied by a normalization of proportions of total T cells and T cell subsets. Four of five uremic patients receiving cimetidine exhibited a marked increase in the percentage of OKT8+ T cells observed in subsequent blood samples with a concomitant increase in immature (OKT4+, OKT8+) lymphocytes that suggested an increase in release of such lymphocytes from the thymus. Assessment of 29 longterm renal allograft recipients by repeated T cell monitoring over an extended period of time confirmed the findings of other investigators that an increase in the OKT4+/OKT8+ ratio was predictive of subsequent allograft rejection episodes while subnormal OKT4+/OKT8+ ratios were indicative of possible cytomegalovirus or herpes virus infections.