A NEW COLORIMETRIC METHOD FOR MEASURING CELL-MEDIATED CYTOTOXICITY INDOGS

In order to replace the radioactive (51)chromium release assay (CRA), a colorimetric method for the determination of cell-mediated cytotoxic ity of natural killer (NK) effector cells of dogs and adherent target cells was developed using the dye Rose Bengal (RE), After a 14 h incub ation period of leucocytes isolated from the peripheral blood (PBL) of dogs and a natural killer cell-sensitive canine adenocarcinoma cell l ine (CTAC), effector and lysed target cells were removed by washing, a nd the surviving adherent target cells were stained with RE. The optic al density (OD) of the remaining target cells was measured in a micros pectrophotometer (ELISA reader) and was found to correspond to the num ber of surviving cells, and thus was inversely correlated to the cytot oxic activity. The RE assay revealed almost identical cytotoxic values when compared with the CRA. In contrast to this assay the RBA is quic k and easy to perform, inexpensive and avoids radioactive materials an d waste. However, the method is restricted to adherent target cells.