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Human leukocyte inhibitory factor (LIF): a lymphocyte mediator with esteratic properties
Sensitized human or guinea pig lymphocytes stimulated by specific antigen or nonspecifically by mitogens elaborate a soluble leukocyte inhibitory factor (LIF) that selectively inhibits the random migration of polymorphonuclear (PMN) leukocytes. LIF has the properties of a protein and is unique among lymphocyte mediators because of its esterase nature. While its natural substrate on PMN leukocytes is unknown, a synthetic amino acid derivative ([3H]benzoyl arginine ethyl ester) has been shown to be capable of serving as an artificial substrate. Through the use of selective esterase inhibitors it may eventually be possible to develop a biochemical assay for its detection in lieu of the biologic assay. LIF-containing supernatants have been shown to enhance a number of PMN leukocyte functions, including adherence, phagocytosis, metabolism, and electrophoretic mobility. In a chemotactic assay, LIF was found to induce the release of a low molecular weight peptide (neutrophil immobilization factor) from PMN leukocytes which decreased their spontaneous random movement and directed movement in the presence of a chemoattractant. This latter pathway may provide an amplification of LIF activity on the migration of PMN leukocytes.
Sensitized human or guinea pig lymphocytes stimulated by specific antigen or nonspecifically by mitogens elaborate a soluble leukocyte inhibitory factor (LIF) that selectively inhibits the random migration of polymorphonuclear (PMN) leukocytes. LIF has the properties of a protein and is unique among lymphocyte mediators because of its esterase nature. While its natural substrate on PMN leukocytes is unknown, a synthetic amino acid derivative ([3H]benzoyl arginine ethyl ester) has been shown to be capable of serving as an artificial substrate. Through the use of selective esterase inhibitors it may eventually be possible to develop a biochemical assay for its detection in lieu of the biologic assay. LIF-containing supernatants have been shown to enhance a number of PMN leukocyte functions, including adherence, phagocytosis, metabolism, and electrophoretic mobility. In a chemotactic assay, LIF was found to induce the release of a low molecular weight peptide (neutrophil immobilization factor) from PMN leukocytes which decreased their spontaneous random movement and directed movement in the presence of a chemoattractant. This latter pathway may provide an amplification of LIF activity on the migration of PMN leukocytes.