LAMININ PEPTIDES STIMULATE HUMAN NEUTROPHIL MOTILITY

Laminin, isolated from Engelbreth-Holm-Swarm tumor, and 10 chemically synthesized peptides, corresponding to various regions of the laminin A and B1 chains, were compared for their abilities to stimulate human peripheral blood polymorphonuclear leukocyte (PMN) chemotaxis and chem okinesis through polycarbonate membrane filters in a 48-well microchem otaxis assay. Peptides F-9, F-ll, F-12, and F-13 were derived from the B1 chain of laminin at the intersection of the cross, and six peptide s were derived from the laminin A chain: peptide TG-1 from the amino-t erminal top globule; peptides GD-1, CD-3, CD-6, and CD-7 from the carb oxyl-terminal globular domain; and peptide AG-1 from above the carboxy l-terminal globular domain. Laminin and the peptides were evaluated ov er a concentration range of 1 to 200 mu g/ml in motility assays. Six o f the peptides, F-9, F-12, GD-1, GD-3, GD-6, and TG-1, stimulated huma n PMN migration in the absence of a gradient (chemokinesis). A fluores cein conjugate of the most active laminin peptide, GD-1, exhibited non specific, nonsaturable binding to PMN. Intact laminin and the other pe ptides failed to stimulate human PMN migration. In contrast, intact En gelbreth-Holm-Swarm laminin stimulated rabbit peripheral blood PMN che mokinesis. These results demonstrate that rabbit and human peripheral blood PMNs have divergent migratory responses to intact laminin. These findings suggest that intact basement membrane laminin does not direc tly stimulate human blood PMN motility in vivo, but that selected lami nin peptide sequences, which may be generated during proteolytic diges tion of laminin, can activate human PMN migration.