Abstract
The tumor growth inhibitory effect of supernatants from peripheral blood mononuclear cells (PBMC) primed with either rIL-2 alone or rIL-2 plus anti-CD 3 Ab was evaluated. PBMC isolated from fourteen healthy donors were cultured with 1, 000 U/ml of rIL-2 to induce LAK cells. LAK cells were stimulated with 10 ng/ml of OKT-3 for first 48 hours of incubation (CD 3 (+) LAK). The inhibitory effect of these cells on tumor growth was evaluated by MTT assay using HT 29 and LS 174 T as target cells. The supernatants from CD 3 (+) LAK inhibited both target cells in a dose dependent fashion, but did not those from ordinaly LAK (CD 3 (-) LAK). The inhibitory effect of the supernatants was not reversed by anti-TNF-alpha and anti-IFN-gamma. This fact indicated that the inhibitory factor in the supernatants from CD 3 (+) LAK was not TNF-alpha nor IFN-gamma. The factor was a molecular weight of 67Kd by the SDS-PAGE analysis and was inactivated at pH3.5 or pH9.5, and also ten minutes heating.
The inhibitory factor was thought to be the same factor as LAK inhibitory factor which was identified, we reported previously, in the supernatants from CD 3 (+) LAK.
