Silencing CD40 in dendritic cells by siRNA

We have previously demonstrated that short interfering RNA (siRNA) is an effective method of gene-specific immune modulation in dendritic cells (DC) (J Immunol 171:691). In this study we investigated the feasibility of generating tolerogenic DC through silencing of CD40, one of the most important costimulatory molecules. Screening of effective siRNA specific to murine CD40 sequence was performed using the novel strategy of siRNA expression cassettes (SEC). Amongst the 4 designed SECs targeting the CD40 sequence (CD40-SEC), two SEC completely and partially suppressed CD40 expression on mature DCs. Functionally, CD40-SEC inhibited allostimulatory activity of DC in mixed lymphocyte culture (MLR). These data suggest that CD40-SEC is a useful tool for generating tolerogenic DC.