Antitumor activity of apoptosis-resistant γδ-T cells demonstrated against human tumor cell lines.

Purified γδ- and αβ-T cells used as effector cells were sorted from 21-day cultures and were routinely enriched from cultures to 97% or greater pure and 98% or greater viable (not shown). To avoid the activation of T cells by the engagement of TCR, γδ-T cells were sorted as αβ-TCR⁻, CD5⁺ cells. Similarly, αβ-T cells were sorted as γδ-TCR⁻, CD5⁺ cells. After sorting, all lymphocytes used as effector cells were cultured overnight in complete RPMI containing 10 U/mL IL-2 and were routinely found to be 95% or greater viable (not shown).⁵¹Cr-labeled tumor cell targets (SK-MEL-5, SK-OV-3, NC-37, HeLa, and K-562) were incubated at the indicated E:T ratios with apoptosis-resistant γδ-T cells (filled circles) or control αβ-T cells (open circles) derived from 2 separate persons (column A and column B, respectively). After a 4-hour incubation at 37°C, supernatants were removed to determine ⁵¹Cr release in cpm. Data are presented as the mean percentage specific target lysis (± SD) of triplicate determinations.