Selective expression of monocyte chemotactic and activating factor/monocyte chemoattractant protein 1 in human blood monocytes by Mycobacterium tuberculosis

Neutrophils are the predominant leukocyte population in acute inflammation. Granulomatous inflammation such as tuberculosis is a specific type of chronic inflammation characterized by the predominant accumulation of macrophages. To clarify the mechanism of cellular recruitment in inflammation, the expression of chemokines, interleukin-8 and monocyte chemotactic and activating factor (MCAF)/monocyte chemoattractant protein 1 (MCP-1), was examined in human blood monocytes in response to lipopolysaccharide of Escherichia coli, which could induce acute inflammation, or purified protein derivative (PPD) or Mycobacterium tuberculosis, which could provoke chronic inflammation. Monocytes stimulated with PPD or M. tuberculosis expressed low levels of antigenic interleukin-8 but high levels of MCAF/MCP-1 compared with monocytes stimulated with lipopolysaccharide. Northern blot analysis showed the early induction of interleukin-8 mRNA and the delayed expression of MCAF/MCP-1 mRNA in response to PPD or M. tuberculosis. Thus, the disparate expression of chemokines may contribute to the cellular recruitment in acute and chronic inflammations.