Increase in sensitivity of the microcytotoxicity assay by T cell growth factor (IL-2)-containing preparations.

Supernatants from Con A-stimulated rat spleen cell cultures containing TCGF were able to increase the sensitivity of the microcytotoxicity assay. Spleen cells from mice immunized with irradiated syngeneic tumour were precultivated for 24 h in a TCGF-containing medium. The precultivated immune spleen cells, when allowed to react with syngeneic tumour target cells, displayed a higher cytotoxic effect than the same immune spleen cells precultivated in a medium without TCGF. Similarly, the addition of TCGF-containing medium to the effector cells during the microcytotoxicity assay increased the cytotoxic effect. Combination of both schedules, i.e., precultivation of the immune effector cells in a TCGF-containing medium and addition of TCGF-containing medium to the effector cells during the microcytotoxicity assay produced the highest increase in sensitivity of the microcytotoxicity assay.