Human tumor cell lines with pleiotropic drug resistance are efficiently killed by interleukin-2 activated killer cells and by activated monocytes.

Two human cell lines, the colon carcinoma Lovo and the transformed intestinal I-407, and their variants (Lovo/Dx and I-407/Dx), with pleiotropic resistance to cancer chemotherapeutic drugs, were examined for their susceptibility to human Interleukin-2-activated killer cells and to activated monocytes. These non-specific or broadly specific effector cells expressed cytotoxicity levels on pleiotropically resistant tumor cells comparable to those of the parental cell populations. This finding provides a rationale for immunological approaches designed to eradicate residual tumor cells surviving and resistant to cytotoxic chemotherapy.