Abstract
Previous studies showed that arginine‐conjugated chitosan (ACS)/DNA nanoparticles (ACGN) mediated significantly higher expression of the transgenes when compared with chitosan (CS)/DNA nanoparticles (CGN). However, the interactions between ACGN and immune cells still remain poorly understood. The present study investigated whether ACGN affected the initial differentiation direction of human naive CD4^+^ T cells, either directly or indirectly. It was demonstrated that both ACGN and CGN induced slightly higher production of IL‐12 by THP‐1 cells in the order of ACGN > CGN. However, this macrophage stimulating activity was much less significant when compared with lipopolysaccharide and did not impact on the differentiation of the naive CD4^+^ T cells separated from the nanoparticles and THP‐1 cells by a 0.1‐μm diameter polycarbonate semipermeable membrane, which allows the pass through of macromolecules including IL‐12. It also demonstrated that, when directly exposed to naive CD4^+^ T cells, none of the nanoparticles induced either the activation of the naive CD4^+^ T cells in the absence of recombinant human IL‐4 (rhIL‐4) or IFN‐γ (rhIFN‐γ) that induce naive CD4^+^ T cell polarization or any changes in the differentiation direction of the naive CD4^+^ T cells in the presence of the corresponding cytokines. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.