Expression of monocyte chemotactic protein-3 in human monocytes exposed to the mycobacterial cell wall component lipoarabinomannan

Monocyte chemotactic protein-3 (MCP-3) is a C-C chemokine which interacts with the CCR1, CCR2 (MCP-1) and CCR3 receptors and has a distinct spectrum of action, The present study was designed to assess whether mycobacterial components were able to induce expression and production of MCP-3 in human monocytes, Mycobacterial lipoarabinomannan (LAM) induced expression of MCP-3 mRNA in human peripheral blood mononuclear cells, The non-mannose-capped version of lipoarabinomannan (AraLAM) was considerably more potent than the mannose-capped version ManLAM or the simpler version phosphatidylinositol mannoside (PIM), Among mononuclear cells, monocytes were responsible for LAM-induced MCP-3 mRNA expression, Whole mycobacteria (Mycobacterium bovis BCG) strongly induced MCP-3 expression, Pretreatment with actinomycin D abolished LAM-induced MCP-3 expression, whereas cycloheximide only partially reduced the expression, LAM-induced MCP-3 expression was associated with the production of immunoreactive PTX3, Interleukin 10 (IL-10) and IL-13 inhibited the induction of MCP-3 by LAM, Thus mycobacterial cell wall components induce expression of MCP-3 in human monocytes, MCP-3, a chemokine active on mononuclear phagocytes, NK cells, T cells and dendritic cells, may be relevant to the induction and expression of immunity against mycobacteria. (C) 1997 Academic Press Limited.