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SGP140: identification of a novel component on human polymorphonuclear leukocyte cell surface involved in chemotactic
Y Yamamoto1, T Yamaguchi, K Sato
1Section of Tumor Cell Biology, Tokyo Metropolitan Institute of Medical Science, Japan.
Abstract:
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.
Insights
Sialoglycoprotein 140 (SGP140) on human polymorphonuclear leukocytes (PMNs) is crucial for chemotaxis and phagocytosis. Blocking SGP140 with antibodies significantly impairs these key immune cell functions.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Sialoglycoprotein 140 (SGP140), a 140 kDa molecule, is the major sialoglycoprotein found on human T-leukemic cell lines.
- SGP140 has been identified on the surface of polymorphonuclear leukocytes (PMNs), which are critical immune cells.
Purpose of the Study:
- To investigate the functional role of SGP140 on human PMNs.
- To determine if SGP140 plays a part in PMN chemotactic and phagocytic activities.
Main Methods:
- Preparation of a specific antibody against SGP140 in rabbits.
- Treatment of PMNs from healthy donors with anti-SGP140 IgG.
- Assessment of PMN chemotaxis, phagocytosis, adhesion, spreading, enzyme release, and superoxide generation.
Main Results:
- Anti-SGP140 IgG treatment significantly diminished PMN chemotactic and phagocytic activities.
- Phagocytosis of both C3- and IgG-opsonized particles were similarly affected.
- SGP140 function is distinct from adhesive glycoproteins like Mac-1, LFA-1, and p150/95 (CDw18).
- Cell adhesion, spreading, enzyme release, and superoxide generation remained unaffected by antibody treatment.
Conclusions:
- SGP140 is a novel molecule expressed on the human PMN cell surface.
- SGP140 plays a significant role in mediating PMN chemotactic and phagocytic activities.
- SGP140 is not involved in leukocyte adhesion reactions, differentiating it from other known adhesion molecules.