SGP140: identification of a novel component on human polymorphonuclear leukocyte cell surface involved in chemotactic and phagocytic activities.

SGP140, which has been isolated as the major sialoglycoprotein of 140 kd molecular weight from a human T-leukemic cell line, was identified on the cell surface of polymorphonuclear leukocytes (PMNs). Specific antibody against SGP140 was prepared in rabbits and was used to probe the function of SGP140 on PMNs in this study. PMNs from healthy donors that were treated with the anti-SGP140 IgG showed remarkably diminished chemotactic as well as phagocytic activity. Phagocytosis of both C3- and IgG-opsonized particles were affected similarly by the antibody treatment. The antibody neither affected cell adhesion and spreading over substrate, nor did it disturb the other functions of PMNs, i.e., enzyme release and superoxide generation. N-formyl-methionyl-leucyl-phenylalanine did not stimulate SGP140 expression on cell surfaces. We present evidence that SGP140 is distinct from the glycoprotein family (Mac-1, LFA-1, and p150/95 [CDw 18]) that performs adhesive reactions of leukocytes. We propose that SGP140 is a novel molecule on the human PMN cell surface that is involved both in chemotactic and phagocytic activities.