Significance of the Mast Cell Response to a Lysosomal Protein

[摘要] The response of local tissue mast cells to the subcutaneous injection of relatively small amounts of cationic protein (or polypeptide) extracted from lysosomes of rabbit PMN has been examined and it was observed that 1) this lysosomal material (LCP) induced a rapid and rather explosive release of the heparin-containing granules from mast cells in a dose-response manner, 2) the shed granules formed relatively stable complexes with the cationic protein in vivo , and 3) the LCP-granule complexes were readily ingested by adjacent connective tissue cells.It is suggested that this LCP-induced degranulation of mast cells may be a naturally-occurring event in the inflammatory process in that mast cells are characteristic constituents of the connective tissue and would, on an occasion of tissue injury, be exposed to this protein after its local release from PMN accumulating in the affected area. Inasmuch as PMN lysosomal substances may be involved in the production of inflammatory injury and heparin can interact with various biologically-active substances, the secretion of heparin-containing granules from mast cells may serve as a local means for the sequestration of these lysosomal proteins for subsequent ingestion by connective tissue cells and in this manner a) reduce the injury-producing potential of these proteins in the tissue and/or b) conserve the antibacterial and hydrolytic properties of these substances for reutilization by the recipient cells and thereby enhance their potential for dealing with phlogogenic stimuli in the tissue (e.g., bacteria).The LCP-induced degranulation of mast cells may thus serve as a local mechanism for control of the inflammatory process and protection against the noxious effects of various cationic agents.

[学科分类] 生物科学（综合）