CR-51 RELEASE ASSAY ADAPTED TO A 96-WELL FORMAT SAMPLE READING

The application of the Matrix 96, a direct beta counter, to monitor ce ll-mediated lympholysis assays (CML) was investigated. Until now, the gamma rays emitted from Cr-51, released in the supernatant of the samp le following lysis of targets by effector cells, were read in gamma co unters using individual tubes for each sample. The Matrix 96 has been designed to count 96 wells simultaneously for assays performed in 96-w ell microplates. Aliquots of supernatants were spotted on a 96-well di sposable metal spotting plate and dried prior to reading in the Matrix 96. A tight correlation was observed between the counts obtained in t he Matrix 96 and a gamma counter, which indicates that the detection o f electron capture beta particles emitted from Cr-51 was as accurate a s reading gamma rays from the same isotope. Both methods confirmed the minimal level of cytotoxicity mediated by unstimulated lymphocytes an d the high levels of nonspecific cytolytic activity mediated by lympho kine-activated killer (LAK) cells against several tumor cell lines.