Properties of Pro‐Inflammatory Cell Type‐Specific Leukocyte Chemotactic Cytokines, Interleukin 8 (IL‐8) and Monocyte Chemotactic and Activating Factor (MCAF)

Inflammation is a host defensive reaction to tissue injuries caused by various conditions such as trauma, infections, invasion of foreign particles, ischemia-reperfusion syndrome, malignant tumors, and autoimmune diseases. The early reactions of inflammations consist of plasma leakage and leukocyte infiltration into the lesion. The types of infiltrating leukocytes depend upon the kind, degree, and timing of tissue injuries. Although several factors such as C5a, leukotriene B4 and bacteriaderived formyl peptides have been long known as leukocyte chemotactic factors, these factors chemoattract any kind of leukocytes, thus suggesting the existence of cell type-specific leukocyte chemotactic factors (28). Over the past several years, numerous members of a new family of heparinbinding polypeptide cytokines with a molecular weight of 8-10 kDa have been identified (Ref. 25) (Table 1) . These factors have 4 cysteine residues at the wellconserved positions and are presumed to possess a similar structure (25). These cytokines are produced massively and rapidly by various kinds of cells in response to inflammatory stimuli including lipopolysaccharide (LPS) , viruses, interleukin 1 (IL-1), tumor necrosis factor (TNF) and so on [Tables 2 and 3 show the cell sources and inducers of interleukin 8 (IL-8) and monocyte chemotactic and activating factor (MCAF) described below]. Furthermore, it has become evident that several of these cytokines have chemotactic activity for specific type(s) of leukocytes, suggesting that these factors are bona fide chemoattractants involved in the leukocyte recruitment seen in the inflammatory processes. These factors are subdivided into two subgroups depending on whether the first two cysteines are separated by a single amino acid or in an adjacent position (Table 1). The former are called intercrine