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 may prove useful for the immunotherapy of cancer. Peripheral blood mononuclear 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. The 3/28 beads were removed after 14 days of culture. Optimal growth conditions 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 demonstrated 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 restimulation with fresh 3/28 beads and displayed nonmajor histocompatibility complex-restricted lytic activity against a variety of human tumor cell lines in standard Cr-51-release assays. Bead removal from COACT cultures before day 14 greatly enhanced the cell growth and cytokine production without significantly affecting the lytic potential. In summary, large numbers of T cells can be generated by coactivation with anti-CD3/anti-CD28-coated beads for 14 days. This method may provide an advantage over current forms of cellular immunotherapy for cancer because of the ability of COACTS to secrete tumoricidal cytokines and generate antitumor cytotoxicity.