Preservation of the helper and suppressor/cytotoxic T-lymphocyte phenotype in continuous culture.

The objective of the present investigation was to culture helper or suppressor/cytotoxic T cell subsets after extensive purification in interleukin 2-containing medium to determine whether phenotype changes for OKT4/91d6- or OKT8/Leu-2a-defined antigens do occur with prolonged culture. Repeated and sequential analysis of such polyclonally activated cultured T cells documented stability of the OKT4/91d6+ and OKT8/Leu-2a+ phenotype. Both populations could be considerably expanded in culture. However, mixing experiments revealed a growth advantage of the OKT8/Leu-2a+ subset. A significant number of cells expressing both phenotypic markers was not detectable. While cultured T cells promoted on interleukin 2 were stable for expression of these functionally important differentiation markers, additional studies on activation antigens revealed high numbers of Tac+ cells at an early time of culture and decreasing numbers during further incubation. The expression of Tac antigen preceded the exponential expansion of the culture. In contrast, the number of cells bearing Ia determinants steadily increased with prolonged culture.