1. Chemiluminescence (CL) of whole blood and isolated polymorphonuclear leucocytes (PMN) from patients with systemic sclerosis (SS) and from age and sex matched controls was measured. CL was induced by the addition of particles (zymosan, latex beads), or phorbol myristate acetate (PMA) or chemotactic peptide (FMLP).
2. Whole blood CL (induced by PMA, zymosan or latex particles) was significantly greater in SS patients than in normal controls.
3. Isolated PMN CL (induced by PMA, FMLP or latex particles) was also significantly greater in the SS patients compared with controls.
4. Increased CL or PMN from patients with SS was mainly observed when luminol was used as amplifier (which detects hydrogen peroxide formation). In most cases, lucigenin-amplified CL of PMN from patients with SS (which detects the primary superoxide anion radical formation) did not differ from the controls.
5. Sera from patients with SS significantly increased both spontaneous and induced CL of normal PMN.
6. Enhanced excitability of PMN to phagocytosis-related stimuli may provide a mechanism for the (leucocyte-mediated) endothelial injury in SS.