COMPARISON BETWEEN THE LUMINOL‐DEPENDENT CHEMILUMINESCENCE OF POLYMORPHONUCLEAR LEUKOCYTES AND OF THE MYELOPEROXIDASE‐HOOH SYSTEM: INFLUENCE OF pH, CATIONS AND PROTEIN

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Abstract
Abstract— Measurements of luminol‐dependent chemiluminescence (CL) from normal human polymorphonuclear leukocytes (PMNL) were carried out and the results were compared to the CL obtained from a cell‐free myeloperoxidase(MPO)‐HOOH‐system.The chemotactic peptide formylmethionyl‐leucyl‐phenyl‐alanine (fMLP) induced a bimodal luminol‐dependent CL response in PMNL, while phorbol myristate acetate (PMA) induced a one‐peak response. Calcium was found to be required for the fMLP but not for the PMA induced response. The absence of glucose reduced the PMA but not the fMLP induced PMNL CL response. Neither calcium nor glucose had any effect on the light emitted from a cell‐free MPO‐HOOH‐system.The PMNL CL response to both fMLP and PMA was affected by the pH‐value, in that at a low pH (6.3) the response was decreased and at a high pH (8.0) the response was increased. These effects were also obtained in cell‐free MPO‐HOOH‐systems. The presence of human serum albumin (HSA) totally inhibited the CL of a cell‐free MPO‐HOOH‐system while, in PMNL CL, HSA reduced only the first phase of the fMLP induced response.The results are discussed in view of the fact that CL is increasingly used as a clinical instrument to study defects in PMNL function and the effects on PMNL function of various agents such as drugs.