A rapid assay for measuring both colony size and cytolytic activity of limiting dilution microcultures

A combined 51Cr-release/MTT dye method is described for accurately measuring cytolytic activity and colony size in the same set of culture microwells. The method was applied to the study of cell-mediated lympholysis (CML) in limiting dilution analysis (LDA) cultures of human PBL from a renal transplant recipient and a healthy control. The results showed that the combined CML/MTT method could detect differences in lytic activity per cell in LDA cultures, and thus is a useful adjunct to standard precursor frequency analysis.