['MicroRNA (miRNA) molecules are potent mediators of post-transcriptional gene silencing that are emerging to be critical in the regulation of innate and adaptive immunity.', 'Here we report that miR-155--an oncogenic miRNA with important function in the mammalian immune system--is induced in dendritic cells (DCs) upon maturation and potentially attenuates their ability to activate T cells. Biolistic epidermal transfection with DNA encoding miR-155 suppressed the induction of antigen-specific T cell-mediated immunity, whereas reduction of endogenous miR-155 by a partially complementary antisense sequence reversed this effect. Because DCs represent a significant component of epidermal tissue and are among the most potent of antigen-presenting cells, the inhibitory actions of miR-155 could be mediated through this subset of cells.'] Does in vivo microRNA-155 expression influence antigen-specific T cell-mediated immune responses generated by DNA vaccination?