ISOLATION OF A LYMPHOCYTE CHEMOTACTIC FACTOR PRODUCED BY THE MURINE THYMIC EPITHELIAL-CELL LINE MTEC1 - IDENTIFICATION AS A 30 KDA GLYCOSYLATED FORM OF MCP-1

A medullary-type murine thymic epithelial cell line (MTEC1) establishe d in our laboratory constitutively produces multiple species of chemot actic factors, which attract lymphocytes, neutrophils, and monocytes, Chemotactic proteins were isolated from MTEC1 supernatant and purified to homogeneity by adsorption to controlled pore glass, heparin-Sephar ose chromatography, cation-exchange FPLC and RP-HPLC. A chemotactic fa ctor for both lymphocytes and monocytes was identified as a 30 kDa pro tein by SDS-PAGE analysis under reducing conditions, After cleavage of the NH2-terminally blocked protein with formic acid, the amino acid s equence of the internal fragment was analysed and found to be identica l to the amino acid sequence of mouse MCP-1/JE, The protein is hence i dentified as a glycosylated natural form of MCP-1/JE secreted by thymi c epithelial cells, The 30 kDa glycosylated form of MCP-1 shows lower specific chemotactic activity (CA) for both lymphocytes and monocytes than the 6-7 kDa unglycosylated form of MCP-1.