Sensitivity of B16 melanoma sublines to lymphokine-activated killer cells as determined by 51Cr-release and clonogenic assays

The aim of this study was to compare the differential sensitivities of B16 melanoma sublines to LAK cells by means of the standard 51Cr release assay and a clonogenic assay, which measures both cell survival and proliferation. LAK cells, generated after 4 days incubation with 150 internatioal units (IU)/ml of interleukin-2 (IL-2), showed both cytolytic and anti-proliferative activities against B16 targets. No differences in subline sensitivity were seen with the 51Cr release assay, but these were observed using the clonogenic assay. An inverse linear relationship existed between % surviving fraction, as determined by the clonogenic assay, and cytolytic activity, as determined by the 51Cr release assay. Our data indicate that the clonogenic assay can detect differences in target cell sensitivity that otherwise are undetectable by the standard 51Cr release assy. The clonogenic assay may prove useful in delineating the long-term anti-adherent and anti-proliferative properties of effector cells from their cytolytic activity. (author). 26 refs.; 4 figs.; 3 tabs