[Cytotoxicity test based on luminescent assay of alkaline phosphatase released from target cells]

Assay of 51Cr release from target cells has been commonly used in various methods of examining the cytotoxic properties of lymphocytes. In this paper a non-isotopic assay of cytotoxicity based on the leak of endogenous alkaline phosphatase (AIP) in target cells, is described. Enzyme activities were assayed by the luminescence on hydrolysis of the lumigen-PPD substrate. P3-X63-Ag8-U1 (P3U-1) cells were demonstrated to contain AIP and proved sensitive to the IL-2-induced killer lymphocytes, while no AIP activity was detected in human effector lymphocytes. Comparative studies of the test with 51Cr- and AIP-release in P3U-1 target cells were carried out, and the results obtained suggested that the AIP release test is useful as a new, simple lymphocyte cytotoxicity test.