The presence and cytotoxicity of CD16+ CD2- subset from PBL and NK cells in long-term IL-2 cultures enhanced by Prothymosin-alpha.

The aim of this study was to characterize the LAK cell subpopulation on which Prothymosin-alpha (ProT alpha) exerts its enhancing effect on cytotoxicity. We investigated the role of ProT alpha on LAK induction from peripheral blood lymphocytes (PBL) and NK-enriched cells, both cultured for 5 weeks with IL-2 and ProT alpha. The different cultures were separated into several subsets throughout the culture time using two color fluorescence activated cell sorting (FACS) and CD56, CD16, CD2 and CD8 monoclonal antibodies. Each cell subset was then tested for cytotoxicity against K562 and Daudi cells. The CD16+ CD2- subset from both, PBL and NK-enriched cells, was the only subset on which ProT alpha had an effect, significantly enhancing this subpopulation. Within the CD16 population, the cells CD16+ CD2+ were the most cytotoxic, although CD16+ CD2- cells were also cytotoxic. ProT alpha only potentiated the cytotoxicity of CD16+ CD2- subset significantly, with 29% and 41% for K562 and Daudi cells, respectively.