Calcein-acetyoxymethyl cytotoxicity assay: Standardization of a method allowing additional analyses on recovered effector cells and supernatants

Cytotoxicity assays provide an in vitro evaluation of the lytic activity of NK and T cells against tumors or transformed cells. However, none of these s methods allow the recovery of cells or supernatants after the assay. We s tandardized a microcytotoxicity test using calcein-acetoxymethyl (calcein-A M) dye that requires very small quantities of cells while maintaining the s ame sensitivity as the traditional Cr-51 assay. The assay is applicable to resting as well as activated human effector cells and uses different target s such as human cell lines that are adherent or growing in suspension and r esistant or sensitive. The most important feature of the method is the poss ibility of recovering cells and supernatants for additional analyses such a s phenotyping and evaluation of soluble factors.