T cells coactivated with immobilized anti-CD3 and anti-CD28 as potential immunotherapy for cancer

This report describes the generation of T cells with characteristics that m ay prove useful for the immunotherapy of cancer. Peripheral blood mononucle ar cells obtained from healthy donors were cultured in the presence of anti -CD3/anti-CD28 mAb-coated beads (3/28 beads) at a 3:1 bead to cell ratio. T he 3/28 beads were removed after 14 days of culture. Optimal growth conditi ons for CD3/CD28 coactivated T cells (COACTS) were determined to be X-VIVO 15 containing 5% human AB serum and 100 IU/ml of interleukin-2. The median fold expansion after 14 days was 84-fold. Flow cytometric analyses demonstr ated that all cultures were >90% CD3(+) with an increase in the proportion of CD8(+) cells. CD28 expression was maintained at very high levels on CD4( +) cells and augmented on CD8(+) cells. COACTS were induced to secrete high levels of Th1-type cytokines (IFN-gamma and TNF-alpha) after a 24-h restim ulation with fresh 3/28 beads and displayed nonmajor histocompatibility com plex-restricted lytic activity against a variety of human tumor cell lines in standard Cr-51-release assays. Bead removal from COACT cultures before d ay 14 greatly enhanced the cell growth and cytokine production without sign ificantly affecting the lytic potential. In summary, large numbers of T cel ls can be generated by coactivation with anti-CD3/anti-CD28-coated beads fo r 14 days. This method may provide an advantage over current forms of cellu lar immunotherapy for cancer because of the ability of COACTS to secrete tu moricidal cytokines and generate antitumor cytotoxicity.