Activation of bone marrow-derived mouse macrophages by bacterial lipopeptide: cytokine production, phagocytosis and Ia expression.

The lipopeptide N-palmitoyl-S-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-(R)-cysteinyl-a lanyl-glycine (Pam3Cys-Ala-Gly), a synthetic analogue of the N-terminal part of bacterial lipoprotein, induces the secretion of interleukin (IL) 1, IL 6 and tumor necrosis factor (TNF)-alpha in bone marrow-derived macrophages that have been cultured in vitro for up to 20 days. IL 6 and TNF-alpha secretion increased from day 6 to day 20 whereas IL 1 secretion increased until day 13 and decreased on day 20. In contrast to the enhancement of cytokine production, phagocytosis of IgG-coated sheep erythrocytes and Ia expression were found to be diminished after treatment with lipopeptide for 24 h. Morphological studies revealed lipopeptide-induced changes of macrophage cultures. The data presented here show the potential of the lipopeptide as a strong activator of bone marrow-derived macrophages.