Chemotactic peptide enhancement of phorbol ester-induced protein kinase C activity in human neutrophils

• Published in: Journal of leukocyte biology 1990-01, Vol.47 (1), p.49-59
• Main Authors: Gay, James C., Stitt, Ella S.
• Format: Article
• Language: English
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Analysis of the immune response. Humoral and cellular immunity; Biological and medical sciences; Calcium - pharmacology; Cytochalasin B - pharmacology; Diglycerides - pharmacology; FMLP; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Immunobiology; Isoquinolines - pharmacology; N-Formylmethionine Leucyl-Phenylalanine - pharmacology; Neutrophils - drug effects; Neutrophils - enzymology; Organs and cells involved in the immune response; oxidative metabolism; phorbol myristate acetate; Phosphorylation; Piperazines - pharmacology; priming; Protein Kinase C - analysis; Protein Kinase C - physiology; Superoxides - metabolism; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0741-5400; 1938-3673
• DOI: 10.1002/jlb.47.1.49

Chemotactic factors and phorbol esters may act synergistically to evoke neutrophil responses, but the mechanism of such interaction is not entirely clear. We investigated the combined effects of the chemotactic peptide n‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP) and phorbol myristate acetate (PMA) on protein kinase C (PKC) activity in human neutrophils. FMLP had little effect on the sharp decrease in cytosolic PKC activity induced by PMA. However, cells exposed to FMLP and PMA exhibited a synergistic increase in particulate PKC activity (1 ± 1 pmol 32P/107 PMNs/min in unstimulated cells, 53 ± 12 pmol 32P with 20 ng/ml PMA, 6 ± 3 pmol 32P with 10‐7 M FMLP, and 191 ± 17 pmol 32P with FMLP and PMA). FMLP also markedly increased calcium/phospholipid‐independent protein kinase activity in particulate fractions of control and PMA‐treated cells. Enhancement of PKC activity required the presence of cytochalasin B during cell stimulation. Cellular calcium was crucial to the FMLP effect since enhancement was decreased in cells incubated with EGTA or Quin2. These results suggest that chemotactic factors and phorbol esters may mediate synergistic effects on neutrophil responses through enhancement of particulate PKC activity. The enhancing effect is probably mediated through chemoattractant‐mediated increases in intracellular calcium.