Effects of bestatin (Ubenimex) on human T-cell colony formation.

The antitumor action of bestatin is considered to be an indirect action mediated by T-cells. Therefore, we investigated the effects of bestatin on the differentiation and proliferation of human precursor T-cells using a colony formation technique. Bestatin did not increase the overall number of T-cell colonies, but it significantly increased in CD4+ cell and significantly decreased in CD8+ cell subpopulations. It also induced CD4+.8+ cells. These findings indicated that bestatin acts on precursor T-cells to induce the differentiation of these cells into CD4+ cells.