Abstract
Susceptibility of LAK cells to K562 cell line was investigated by HTCA (human tumor cell clonogenic assay), when target cells were pretreated with antineoplastic drugs. Percent inhibition of colony formation as cytotoxic effect of LAK cells and antineoplastic agents was significantly higher than that of LAK cells or antineoplastic agents alone. This susceptibility of combination of LAK cells with antineoplastic agents was additivism. The cytotoxicity of LAK cells was not affected by antineoplastic agents, enen when target cells were treated concurrently with antineoplastic agents. The susceptibility of LAK cells against intermittent drug-exposure K562 cells as a resistant cell line was investigated. Percent inhibition of colony formation of LAK cells against CDDP and MMC resistant K562 cell lines were significantly higher than that of parent K562 cell line. To investigate the difference of tumor-binding capacity and recognition of LAK cells against these cell lines, direct conjugate forming assay and cold target inhibition assay were examined. As a result of these assays, recognizing ability of LAK cells against resistant cell line was lower than that of parent cell line in opposition to inibitory effect of colony forming. Then we investigated the difference of membrane fragility of these cell lines. NP-40, a non-ionic detargent of membrane, was incubated with these cell lines. Consequently, the cell membrane of CDDP resistant cell line was more fragile than that of K562 cell, and it is suggested that the difference of susceptibility against these cell lines may be induced by membrane fragility.
