IDENTIFICATION OF MOUSE GRANULOCYTE CHEMOTACTIC PROTEIN-2 FROM FIBROBLASTS AND EPITHELIAL-CELLS - FUNCTIONAL COMPARISON WITH NATURAL KC ANDMACROPHAGE INFLAMMATORY PROTEIN-2

Neutrophil and monocyte chemotactic factors were isolated from conditi oned media of mouse fibroblasts and epithelial cells. Neutrophil chemo tactic activities were purified to homogeneity using a four-step chrom atographic procedure, and the corresponding proteins were identified b y amino acid sequence analysis. Natural forms of the murine chemokines KC and macrophage inflammatory protein-2 were isolated from virus-inf ected fibroblasts. However, the major neutrophil chemotactic activity from fibroblasts stimulated with endotoxin plus double-stranded RNA an d from PMA-treated epithelial cells resided in other 7- and 8-kDa prot eins, Amino acid sequence analysis revealed a novel Cys-Xaa-Cys chemok ine structure, characterized by the conservation of four cysteines and the Glu-Leu-Arg motif. Based on the completely identified primary str ucture of this natural protein, this chemokine must be considered to b e the murine homologue of human and bovine granulocyte chemotactic pro tein-2 (GCP-2; 61 and 64% identical residues, respectively). Due to NH 2-terminal cleavage, 11 different forms of mouse GCP-2 were discovered , In contrast to human and bovine GCP-2, functional comparison of long and short NH2-terminal forms of mouse GCP-2 demonstrated that truncat ed mouse GCP-2 (short form) has a higher specific activity in neutroph il activation (gelatinase B release) and chemotaxis assays. Furthermor e, moose GCP-2 was more potent than human GCP-2 on human neutrophils, and more active than murine KC and macrophage inflammatory protein-2 o n mouse neutrophils. In view of the absence of a murine homologue for IL-8, NH2-terminally processed GCP-2 can be considered a major neutrop hil chemoattractant in the mouse during the inflammatory response.