To establish whether degranulation is an important prerequisite for granulocyte (PMN) aggregation, we employed the chemoattractant synthetic peptides Gly-His-Gly (GHG) and n-formyl-Met-Leu-Phe (FMLP). As previously shown, GHG caused chemotaxis of PMN at 10 ug/ml. GHG at concentrations of 10, 15, and 50 ug/ml did not cause degranulation of cytochalasin (CB)-treated PMN beyond that observed for control as measured by the percent total release of the granular constituent lysozyme into supernate (GHG 8.4%; control 8.7%). GHG also did not cause release of the cyto-plasmic constituent LDH (GHG 5.9% of total; control 4.0%). GHG (range 12.5 to 100 ug/ml) also did not induce aggregation of CB-treated PMN as measured by light scattering. In contrast, 2×10-7M FMLP provoked the release of lysozyme (33% of total) from granules, but not release of LDH (5.3% of total), and caused aggregation of CB-treated PMN. When CB-treated PMN were incubated with GHG (15 ug/ml) followed by FMLP, there was no inhibition of lysozyme release (29.2% of total) nor of PMN aggregation. These studies suggest that GHG and FMLP interact with the PMN at distinct loci. Although GHG is chemotactic for PMN it failes to induce PMN aggregation, probably through its inability to provoke degranulation.
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Boxer, G., Allen, J., Baehner, R. et al. 793 DISSOCIATION OF THE NEUTROPHIL FUNCTION OF CHEMOTAXIS FROM DEGRANULATION AND AGGREGATION. Pediatr Res 15, 574 (1981). https://doi.org/10.1203/00006450-198104001-00817