Antitumoral effects of Pseudomonas aeruginosa lectins on Lewis lung carcinoma cells cultured in vitro without and with murine splenocytes.

Examination of the in vitro effects of PA-I and PA-II lectins of Pseudomonas aeruginosa on Lewis lung carcinoma cells revealed that these lectins differ in their effects. PA-I, the galactophilic lectin, exhibited both cytotoxic and cytostatic activities on these cells (tested by [3H]thymidine incorporation and by crystal violet vital staining). The two activities were dose and time dependent and inhibitable by the addition of methyl-alpha-D-galactoside to the culture medium. PA-II, the L-fucose and D-mannose binding lectin of the same Pseudomonas strain did not exhibit such a direct toxic effect on the tumor cells but affected them in the presence of splenocytes. Its addition to the tumor cells cocultured with murine (C57B1) splenocytes led to a profound cytolysis of the tumor cells, an effect which was inhibited by L-fucose.