C5a-Induced Chemiluminescence of Human Granulocytes and its Amplification by a Serum Factor

Abstract

Purified human C5a elicits a fast chemiluminescence (CL) response from isolated human granulocytes in the presence of Lucigenin (bis-N-methylacridinium nitrate). The reaction is inhibitable to more than 90 % by superoxide dismutase (SOD) — final concentration 200 μg/ml —, to about 60 % by catalase — final concentration 10 mg/ml — and to 30 % by the hydroxyl radical scavenger D-mannit — final concentration 100 mM. Therefore O2− seems to be the oxygen radical responsible for most of the CL, while •OH and H2O2 are also involved.Addition of normal pool serum to the cells for 1–2 min before stimulation with C5a strongly enhances the effect in a dose and time-dependent manner. Therefore the existence of a «helper activity» in serum amplifying the C5a-induced CL of granulocytes is postulated. This «helper activity» is, however, not specific for C5a, since CL responses elicited with the chemotactic peptide f-met-phe or by phorbol-myristate-acetate (PMA) are also enhanced by preincubation with serum. In contrast, ConA-induced CL is not enhanced but decreased. Therefore, though not unique to C5a-induced CL, the «helper activity» seems not to represent a «general adjuvans» effect of serum on the granulocytes, but to be restricted to certain stimuli.