The formylpeptide chemotactic receptor on rabbit peritoneal neutrophils: change of receptor affinity and number by L-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK).

Pretreatment of rabbit peritoneal neutrophils at 37 degrees with 10-35 microM L-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK) decreases by 20-50% the detectable number of f Met-Leu-[3H]Phe binding sites. Greater TPCK concentrations, between 50 and 100 microM, cause less of a decrease or actually increase peptide binding activity to a level greater than that of untreated cells. Furthermore, Scatchard analysis indicates that the sites detected on neutrophils after TPCK treatment have 1.2-3.2 fold lower apparent Kd (higher affinity) than those detected on untreated, control cells (1.1 +/- 1.7 X 10(-8) M vs 1.7 +/- 1.5 X 10(-8) M, P less than 0.02). Thus, TPCK treatment of rabbit peritoneal neutrophils causes both a decrease in f Met-Leu-[3H]Phe receptors and increases the affinity of the remaining sites. In addition, peritoneal neutrophils incubated at 37 degrees without TPCK were found to rapidly express additional f Met-Leu-[3H]Phe receptors. These additional sites, however, were not evident on neutrophils incubated at 37 degrees with TPCK. Concomitantly with the expression of additional sites, neutrophils placed at 37 degrees were found to spontaneously release small amounts of lysozyme. However, since equivalent amounts of lysozyme were released by cells incubated with or without TPCK, we are unable to state whether expression of the additional sites is due to neutrophil degranulation. Finally, although rabbit peripheral blood neutrophils also show an increase in binding sites at 37 degrees, treatment of these cells with TPCK does not cause a decrease in their f Met-Leu-[3H]Phe binding activity.