Transgenic expression of CD40L and interleukin-2 induces an autologous antitumor immune response in patients with non-Hodgkin's lymphoma

The malignant B cells of non-Hodgkin's lymphoma (B-NHL cells) express pepti des derived from tumor-specific antigens such as immunoglobulin idiotypes, and also express major histocompatibility complex antigens. However, they d o not Express costimulatory molecules, which likely contributes to their pr otection from host antitumor immunity. To stimulate NHL-specific immune res ponses, we attempted to transfer the human CD40 ligand (hCD40L) gene to B-N HL cells and enhance their costimulatory potential. We found that an adenov iral vector encoding human CD40L (AdhCD40L) was ineffective at transducing B-NHL cells because these cells lack the coxsackievirus B-adenovirus recept or and alpha (v) integrins. However, preculture of the B-NHL cells with the human embryonic lung fibroblast line, MRC-5, significantly up-regulated ex pression of integrin alpha (v)beta3 and markedly increased their susceptibi lity to adenoviral vector transduction. After prestimulation, transduction with AdhCD40L increased CD40L expression on B-NHL cells from 1.3 +/-0.2% to 40.8 +/- 11.9%. Transduction of control adenoviral vector had no effect. E xpression of transgenic human CD40L on these CD40-positive eel Is was in tu rn associated with up-regulation of other co-stimulatory molecules includin g B7-1/-2. Transduced B-NHL cells were now able to stimulate DNA synthesis of autologous T cells. However, the stimulated T cells were unable to recog nize unmodified lymphoma cells, a requirement for an effective tumor vaccin e. Based on previous results in an animal model, we determined the effects of combined use of B-NHL cells transduced with AdhCD40L and AdhlL2 vectors. The combination enhanced initial T-cell activation and generated autologou s T cells capable of specifically recognizing and killing parental (unmodif ied) B-NHL cells via major histocompatibility complex-restricted cytotoxic T lymphocytes. These findings suggest that the combination of CD40L and IL2 gene-modified B-NHL cells will induce a cytotoxic immune response in vivo directed against unmodified tumor cells.