NEUTROPHIL FORMYL-PEPTIDE RECEPTORS - RELATIONSHIP TO PEPTIDE-INDUCEDRESPONSES AND EMPHYSEMA

A reproducible assay was established to assess the number of formyl-pe ptide receptors expressed on the surface of human polymorphonuclear le ukocytes (PMN). Using this assay the number of receptors was shown to demonstrate wide within- and between-subject variability. However, the receptor numbers were related to the chemotactic response (r = 0.572) and degranulation response (r = 0.512) to the peptide formyl-methiony l-leucyl-phenylalanine. Subsequent studies showed increased receptor n umbers on PMN from patients with emphysema (median, 459 x 10(3)/cell; range, 207 to 1,080) as compared with age-matched control subjects (me dian, 288; range, 168 to 519; p < 0.02), which may explain the increas ed chemotactic response of the PMN to formyl peptides. This difference was not observed in patients with bronchiectasis, suggesting that the increased receptor number is a feature of emphysema. Furthermore, the increase was largely a feature of smokers with emphysema (median, 463 ; range, 362 to 1,080), whereas age-matched smokers without emphysema had lower numbers of receptors (p < 0.001; median, 332; range, 243 to 411). This observation suggests a mechanism that may explain the susce ptibility of some smokers to the development of emphysema.