Further evidence for autonomy of T cells mediating specific in vitro cytotoxicity: Efficiency of very small amounts of highly purified T cells

Abstract

Cytotoxic educated thymus cells were either incubated in a plastic flask or in the presence of iron with subsequent magnetic removal of iron-containing cells or subjected to a combination of both treatments. Acridine orange staining showed that the resulting purified cells contained about one macrophage per 5 × 10 4 cells. More generally, their content of non-T cells was less than 1%, as judged by the proportion of cells resistant to anti-θ antiserum in the presence of complement. Improvements in the 51Cr-release Cytotoxicity test allowed us to demonstrate a significant cytotoxicity of as few as 10 3 of these highly purified T cells. Under these conditions, any participation by macrophages or other non-T cells in T cell-mediated cytotoxicity could be excluded.