Human T lymphocytes grown in T-cell growth factor: functional attributes in MLC, CML, PLT and allogeneic suppression

Conditions for the production of highly effective human T-cell growth factor (TCGF) and its screening in a thymidine incorporation assay are described. Culture medium supplemented with optimum concentrations of TCGF was used in bulk culture systems for the expansion of alloactivated and non-alloactivated T-cell populations. Surface marker studies of cells grown in TCGF-dependent culture showed that the majority were T cells expressing DR antigens. These cells retained their proliferative responsiveness in mixed leucocyte cultures but were unable to stimulate proliferation of normal allogeneic lymphocytes. Cultured cells which derived from mixed leucocyte cultures retained immunological specificity compared with cells not exposed to TCGF both in terms of proliferative responses caused by allogeneic cells in the absence of TCGF, and in terms of cytotoxic activity against 51Cr-labelled target cells. In addition they were capable of suppressing tritiated thymidine incorporation in mixed leucocyte cultures. These experiments show that continuous culture with TCGF can expand a variety of T-cell subpopulations with retention of distinct immunological function.