Stimulus Specific Induction of Monocyte Chemotactic Protein-1 (MCP-1) Gene Expression

Abstract

The movement of blood monocytes from the peripheral vasculature into an area of inflammation is an ill defined process. Typically the recruitment of monocytes is associated with a characteristic temporal delay, as these mononuclear phagocytes are histologic markers of chronic cell-mediated responses or delayed type hypersensitivity reactions. While monocytes are typical cells that are found in cell mediated inflammatory lesions, neutrophils are conspicuous by their absence in these lesions. This observation is important for a number of reasons. First, it is apparent that different inflammatory cells are required to perform different functions during the development and maintenance of different inflammatory responses. Second, the low numbers of monocytes in acute inflammatory lesions and high numbers associated with chronic inflammation suggests that specific recruitment signals are expressed to coincide with acute or chronic inflammation. Finally, redundancy exists with regard to chemotactic factors. This is especially true of those chemotactic factors which exhibit activity for more than one population of inflammatory cells. For example, a number of well studied chemotactic factors, such as C5a, leukotriene B4, and fMLP, are potent agents for the movement of both monocytes and neutrophils (Table 1). As mentioned above, monocytes and neutrophils are relatively faithful markers for chronic and acute inflammation, respectively.