Sézary syndrome: phenotypic and functional characterization of the neoplastic cells.

Phenotypic properties of the neoplastic cells in skin, blood and lymph node specimens from 5 patients with the Sézary syndrome were examined by immuno-enzymatic and -fluorescence labelling of cells and tissue sections with a monoclonal antibody panel. In 3 cases, the in vitro functional properties of the neoplastic cells (isolated from blood specimens) were also analysed using a reverse plaque-forming cell assay. 3 different immunological categories were identified as follows: T-helper/inducer neoplasms (3 patients); T-suppressor/cytotoxic neoplasms (1 patient); and neoplastic T-cells demonstrating characteristics consistent with a concept of their derivation from inducible suppressor T-cells (1 patient). These data provide conclusive evidence that Sézary syndrome is heterogeneous with respect to the immunological characteristics of the neoplastic cells.