An OKT4+ T‐Cell Population with Suppressor Activity in Sézary Syndrome

This report describes a case of Sézary syndrome with the surface marker phenotype of a mature distinct T‐cell subset OKT3+. OKT4+. OKT8−. OKT17+. OKIal−(+). Functional studies indicated that the patient's peripheral blood cells showed a very low proliferative response to non‐specific milogens (phytohaemagglutinin. concanavalin A. pokeweed mitogen) and failed to differentiate into plasma cells in a pokeweed mitogen—immunoglobulin‐synthesis‐driven system. In coculture with normal cells the leukuemic cells were able to suppress lectin‐induced T‐cell proliferation and B‐cell differentiation in a dose‐dependent manner. Suppressor function was not radiosensitive and did not require the presence of the OKT8+ subset for expression. These Sézary cells thus represent a suppressive T‐cell subset within the OKT4+ population. This subset may well correspond to the recently described OKT4+. OKT17+ normal suppressor cells. These findings would therefore illustrate a pathological and possibly clonal expansion of a normal OKT4+ suppressor T‐ceil subset.