In this study the effect of various Protein kinase C (PKC) activators/tumour promoters on the maturation and activity of human peripheral blood monocytes was examined. Monocytes were cultured in the absence or presence of various PKC activators for up to 2 weeks, and examined for the number of adherent cells, expression of myeloperoxidase enzymes, CD14 antigens, mannose/N-acetylglucosamine (Man/GlcNAc) receptors, and the production of TNF-alpha. The presence of PKC activators in cultures of monocyte-derived macrophages (HuMoDM) prevented the loss in the number of initially plated monocytes, otherwise observed in long-term tissue cultures with time of incubation. This effect of PKC activators on monocyte survival was diminished in the presence of PKC inhibitors. HuMoDM obtained in the presence of PKC activators maintained a normal differentiation pattern, as was evident by the loss of granular myeloperoxidase enzymes and CD14 antigens, and the acquisition of membrane Man/GlcNAc receptors. HuMoDM which differentiated in the presence of PKC activators also released TNF-alpha in comparable amounts to freshly harvested human monocytes. PKC activators/tumour promoters augmented the viability of long-term cultures of human monocyte-derived macrophages. Such macrophages may facilitate cell and molecular biology studies of differentiated human macrophages.

Tissue cultures are widely used to study the relationship between various bacteria and tissue cells. Previous studies concerning growth of leptospirae in cell culture have elucidated no stimulatory growth factors (Ellison et al. 1965; Haxington & Sleight, 1966; Miller, Miller & White, 1966; Finn & Jenkin, 1973). Our results indicate that the cell lines (Clone By BHK 2 1 and HK) and primary cells (PMK, CEF) may markedly enhance the growth of leptospirae in some media. METHODS Test organisms. Avirulent and virulent strains of Leptospira serotype icterohaemorrhagiae were used. The avirulent Wijnberg strain was obtained from Dr Esther Shenberg, WHO/ F A