Phenotypic evolution of CTL B-lines in vitro.

This study demonstrates that cytolytic T-cell lines exhibit progressive in-vitro modifications of their phenotype and of their growth behaviour and may use different pathways for their multiplication. Comparing three established cell lines, we firstly demonstrated that the expression of LFA-I is stable but the Lyt 2, 3 is rapidly lost. In this case, a high lectin-dependent cytotoxicity appears. Secondly, we demonstrated that two of the cell lines used the interleukin 2-interleukin 2 receptors (IL-2-IL-2R) binding pathway. Two different monoclonal antibodies showed that the IL-2 receptors distribution does not correlate with the number of functional sites which determines the IL-2 requirement. In contrast, the third cell line, although bearing high levels of IL-2 receptors, grows without the addition of IL-2; this cell growth is not inhibited by anti-IL-2 receptors monoclonal antibodies. Thirdly, it appears that the new property of IL-2 independence is associated with acquisition of the simultaneous capacity to induce tumour grafts in nude mice. As it has been recently reported that cytolytic T-lymphocytes against tumour cells could be promising immunotherapeutic agents, the spontaneous malignant transformation of such CTL lines should be taken into account before using them for adoptive immunotherapeutic purposes.