Cytotoxicity of rabbit macrophage peptides MCP-1 and MCP-2 for mouse tumor cells

The cytotoxicity of cationic peptides MCP-1 and MCP-2 isolated from rabbit alveolar macrophages was tested against two tumor cell lines of murine lymphosarcoma origin, RAW117-P and RAW117-H10, and a normal mouse connective tissue fibroblast strain, ATCC CCL1.RAW117-H10 is a highly malignant metastatic variant derived from the less malignant RAW117-P. Our results indicate that these peptides possess a cytotoxic activity against the tumor cells tested but not against the normal cells tested. At concentrations of 30 micrograms/ml, these peptides completely killed RAW117-H10 cells in suspension cultures, while inhibiting growth of RAW117-P for but a limited period of time, up to 48 h, after which growth resumed. RAW117-P cells were killed by concentrations of 40 micrograms/ml. These peptides showed little cytotoxicity for normal mouse connective tissue fibroblasts at concentrations of 40 micrograms/ml.