Heparin induces differentiation of CD1a+ dendritic cells from monocytes: phenotypic and functional characterization

Dendritic cells (DCs) play important roles in initiation and regulation of immune responses. DCs derived from human monocytes can be classified according to presence of CD1a molecules. Although CD1a+ DCs can be prepared from monocytes in media containing GM-CSF, IL-4, and FCS, it has been reported that CD1a+ DCs could not be easily obtained from monocytes using media containing human serum or plasma. In this study, we demonstrate for the first time that heparin can reliably induce differentiation of CD1a+ DCs from monocytes with or without autologous serum or plasma. The development of CD1a+ DCs is heparin concentration dependent (0-50 U/ml). Comparing with CD1a- DCs developed without heparin, CD1a+ DCs express higher CD40 and CD80 and lower CD86. Both CD1a+ and CD1a- DCs express similar levels of HLA-DR. CD80, CD86, HLA-DR, and CD40 are proportionally up-regulated when both types of DCs are stimulated with LPS or LPS plus IFN-gamma. The effect of heparin is neutralized by heparin-binding proteins, such as protamine sulfate, platelet factor-4, and beta-thromboglobulin. Functionally, heparin-treated DCs respond to LPS or LPS plus IFN-gamma with higher IL-10 and less IL-12 production than heparin-untreated DCs. Heparin-treated DCs are more potent in priming allogeneic and autologous CD4+ T cells to proliferate and to produce both type 1 and type 2 cytokines. The results of our study show that CD1a+ DCs can be prepared from monocytes ex vivo without using xenogeneic serum and may be used for immunotherapy.