ANTIGEN-DEPENDENT CD28 SIGNALING SELECTIVELY ENHANCES SURVIVAL AND PROLIFERATION IN GENETICALLY-MODIFIED ACTIVATED HUMAN PRIMARY T-LYMPHOCYTES

Most tumor cells function poorly as antigen-presenting cells in part b ecause they do not express costimulatory molecules. To provide costimu lation to T lymphocytes that recognize tumor cells, we constructed a C D28-like receptor specific for G(D2), a ganglioside overexpressed on t he surface of neuroblastoma, small-cell lung carcinoma, melanoma, and other human tumors. Recognition of GD, was provided by a single-chain antibody derived from the G(D2)-specific monoclonal antibody 3G6. We d emonstrate that the chimeric receptor 3G6-CD28 provides CD28 signaling upon specific recognition of the G(D2) antigen on tumor cells. Human primary T lymphocytes retrovirally transduced with 3G6-CD2S secrete in terleukin 2, survive proapoptotic culture conditions, and selectively undergo clonal expansion in the presence of an antiidiotypic antibody specific for 3G6-CD28. Polyclonal CD8(+) lymphocytes expressing 3G6-CD 28 are selectively expanded when cultured with cells expressing alloge neic major histocompatibility complex class I together with G(D2). Pri mary T cells given such an antigen-dependent survival advantage should be very useful to augment immune responses against tumor cells.