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.