Formylmethionyl-leucyl-phenylalanine-induced chemiluminescence responses in bovine polymorphonuclear leukocytes

Isolated bovine polymorphonuclear leukocytes (PMNL) show a biphasic luminol-dependent chemiluminescence response, and when exposed to high concentrations (2 x 10(-4) M) of the chemotactic peptide formylmethionyl-leucyl-phenylalanine (f-Met-Leu-Phe), the second emission peak is enhanced. This response was increased in magnitude by incubating PMNL at room temperature before stimulation with f-Met-Leu-Phe. Pre-exposure of bovine PMNL to myeloperoxidase (MPO) also enhanced their receptiveness to the chemotactic peptide, indicating that the MPO-hydrogen peroxide system can modulate the bovine PMNL response to chemotactic factors. The results demonstrate that bovine PMNL are stimulated by the chemotactic peptides to participate in inflammatory processes.