GENERATION OF STABLE MONOCYTE-DERIVED DENDRITIC CELLS IN THE PRESENCEOF HIGH-CONCENTRATIONS OF HOMOLOGOUS OR AUTOLOGOUS SERUM - INFLUENCE OF EXTRACELLULAR PH

Recent studies have highlighted the high degree of differentiation of monocytes. Indeed, dendritic cells (DC) can be generated from monocyte s, in the presence of appropriate cytokines. However, human serum is u sually avoid in such cultures. Here, we report that human serum does n ot inhibit generation of mature DC from blood monocytes, but rather th at extra-cellular pH may play an important role in the regulation of m onocyte differentiation. Indeed, monocytes cultured at pH 7.4 in the p resence of high concentrations of human serum developed efficiently in to mature DC, as opposed with monocytes cultured at pH 7. These pH 7.4 cultured DC present ed features characteristic of mature DC, at the p henotypical, functional and morphological levels. In addition, these D C were stable, with respect to their sustained expression of CD83 and CD86, upon withdrawal of cytokines. Finally, when autologous plasma wa s used instead of homologous serum, differentiation of monocytes imo m ature DC was efficient, as well. Thus, altogether, our data show the i mportance of extra-cellular pH on differentiation of monocyte-derived DC in the presence of human serum, which should be maintained at plasm a levels. (C) American Society for Histocompatibility and Immunogeneti cs, 1998. Published by Elsevier Science Inc.