Regulatory activity of neoplastic T cells in Sezary syndrome on in vitro immunoglobulin production

Functional activities and surface markers of the neoplastic T cells of three patients with Sézary syndrome were studied and compared with the functional activities of OKT4 + and OKT8 + T-cell subsets from healthy donors. The neoplastic T cells of the patients had the following marker phenotype: OKT1 +3 +4 +6 −8 −11 + 17 +I1 −M1 −3A1 −. In contrast to healthy donor OKT4 + T cells, none of the neoplastic T cells had significant helper activity on pokeweed-mitogen-driven Ig synthesis. In one patient the neoplastic T cells suppressed pokeweed-mitogen-driven Ig synthesis. The suppression by the patient cells did not require the presence of radiosensitive OKT4 + suppressor-inducer cells in the culture. It is concluded that OKT4 +8 −3A1 − neoplastic T cells from Sézary-syndrome patients lacking helper activity are more common than previously thought and that in some cases the OKT4 −8 −3A1 − Sézary cells can mediate suppressor activity.