Figure 1.

Susceptibility of MDA-MB-231 breast carcinoma cell lines to human LAK CML (⁵¹Chromium-release data). 2 × 10⁶ PBMC/ml were incubated with 1000 U/ml human rIL-2 in RPMI 1640 containing 10% autologous plasma in a total volume of 10 ml. After 5 days, these cells were harvested and set up in an 18 hr ⁵¹Cr-release assay to measure the cytotoxicity against MDA-MB-231 (drug-sensitive breast carcinoma cell line), MPAM-26 (murine MDR-1 transfected), and Vcr10 (MPAHS-1-10), Vcr300 (MPAHS-1-300), Dox150 (MPAHS-DOX150), human P-gp transfected multidrug resistant variants of MDA-MB-231. Percent specific cell-mediated lysis was plotted against effector/target ratio based on data obtained from one experiment representative of 15 independent experiments performed by three independent investigators. The data from the 15 experiments were converted to lytic units and tested for significant difference (see text).