DIFFERENTIAL-EFFECTS OF LPS AND CD40 LIGAND STIMULATIONS ON THE INDUCTION OF IL-12 PRODUCTION BY DENDRITIC CELLS AND MACROPHAGES

In this experiment, we have examined the IL-12 production of murine ma crophages (M phi) and dendritic cells (DC) in response to LPS and CD40 ligand (CD40L) stimulations. Splenic M phi and DC were purified by so rting on the basis of Mac-1 and CD11c expression and stimulated with L PS or Chinese hamster ovary cells expressing CD40L. The results showed that the ligation of CD40 induced the enhancement of IL-12 p40 mRNA a ccumulation and IL-12 production in DC as well as in M phi; however, n either the accumulation of IL-12 p40 mRNA nor the production of bioact ive IL-12 was detected in DC stimulated with various concentrations of LPS, although M phi produced IL-12 on LPS stimulation. There was a re markable difference in the expression of LPS receptor CD14 between M p hi and DC. M phi evidently expressed CD14 but the CD14 expression of D C was quite low. Possible mechanisms of the failure in IL-12 productio n of DC are discussed. (C) 1997 Academic Press.