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° with 10–35 μM 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 μM, 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 K d (higher affinity) than those detected on untreated, control cells (1.1±1.7×10 −8 M vs 1.7±1.5×10 −8 M, p