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 chemokinesis through polycarbonate membrane filters in a 48-well microchemotaxis assay. Peptides F-9, F-11, F-12, and F-13 were derived from the B1 chain of laminin at the intersection of the cross, and six peptides were derived from the laminin A chain:peptide TG-1 from the amino-terminal top globule; peptides GD-1, GD-3, GD-6, and GD-7 from the carboxyl-terminal globular domain; and peptide AG-1 from above the carboxyl-terminal globular domain. Laminin and the peptides were evaluated over a concentration range of 1 to 200 μg/ml in motility assays. Six of the peptides, F-9, F-12, GD-1, GD-3, GD-6, and TG-1, stimulated human PMN migration in the absence of a gradient (chemokinesis). A fluorescein conjugate of the most active laminin peptide, GD-1, exhibited nonspecific, nonsaturable binding to PMN. Intact laminin and the other peptides failed to stimulate human PMN migration. In contrast, intact Engelbreth-Holm-Swarm laminin stimulated rabbit peripheral blood PMN chemokinesis. 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 directly stimulate human blood PMN motility in vivo, but that selected laminin peptide sequences, which may be generated during proteolytic digestion of laminin, can activate human PMN migration.