An antiproliferative salicylaldoximato type copper(II) chelate as an enhancer of the cytotoxicity of murine spleen cells to tumor cells in vitro

The antiproliferative metal chelate bis(2,3,4-trihydroxybenzaldoxyimato)copper(II) (CuTRI2) was shown to distinctly enhance the cytotoxicity of the spleen effector cells of CBA/CA mice to YAC-1 tumor cells in vitro as measured using a 4-h 51Cr release test. The compound was either added directly to the assay system or the effectors were incubated in the presence of it for 2 h and washed before assay. The concentrations tested were 10, 20 and 40 mg/ml, the lowest concentration leading invariably to the strongest enhancement of cytotoxicity. The effector cells involved were very probably natural killer cells. The highest concentration had, if anything, a negative effect on the release of 51Cr from the target cells. In the same concentrations, CuTRI2 did not enhance the cytotoxicity of the spleen effector cells to K-562 tumor cells. Preliminary studies on the related chelate trans-bis(2,4-dihydroxybenzaldoximato)copper(II) are also reported. This paper is apparently the first report of a copper chelate that enhances the cytotoxicity of any sort of effector cells to tumor cells.