Comparison between clonogenic and cytotoxic assays for measuring LAK cell activity.

The antiproliferative effect of lymphokine-activated killer (LAK) cells was studied using a clonogenic assay in an attempt to find a model for predicting this effect in vivo or ex vivo (in the case of purging) in cancer treatment. The results were compared with the standard 51Cr-release cytotoxic assay. Cells from clonogenic neoplastic cell lines (K562 and HL-60) were plated in methylcellulose with LAK cells obtained from ten different donors in various effector-to-target (E:T) ratios. At E:T ratios of 16:1, elimination of greater than 90% of the clonogenic cells was seen in 20 of 21 experiments, whereas such lysis was incidentally found in the 51Cr-release assay. In almost all paired combinations, clonogenic cells tested in a colony assay were more sensitive to kill by LAK cells than the whole tumor cell suspensions measured in the 51Cr-release assay.