Potency of mature CD40L RNA electroporated dendritic cells correlates with IL-12 secretion by tracking multifunctional CD8(+)/CD28(+) cytotoxic T-cell responses in vitro.

Electroporation of mature dendritic cells (DC) with RNA-encoding CD40L greatly enhances the production of interleukin (IL)-12, a proinflammatory cytokine necessary for the induction of T-cell immunity. Results presented herein reveal a correlation between the priming of CD28(+) antigen-reactive effector memory cytotoxic T lymphocytes (CTL) displaying 3 or 4 simultaneous effector functions and the quantity of IL-12 produced by postmaturation electroporation-CD40L DC. By using multiparameter flow cytometry, the quantities of IL-12 needed to prime naive antigen-reactive T cells to simultaneously produce interferon-γ and tumor necrosis factor-α in the presence or absence of IL-2 secretion in conjunction with lytic activity defined by CD107a expression can be used to determine the overall potency of a DC product. In the presence of IL-12, CTL differentiation toward lytic function is not accompanied by a reduction in the secretion of interferon-γ and tumor necrosis factor-α. Therefore, by measuring the availability of IL-12 one can predict the potency of a DC immunotherapeutics in relation to its ability to drive distinct effector memory CTL subsets with multifunctional activities.