CHEMILUMINESCENCE OF HUMAN POLYMORPHONUCLEAR LEUKOCYTES AFTER STIMULATION WITH WHOLE CELLS AND CELL-WALL COMPONENTS OF STAPHYLOCOCCUS-EPIDERMIDIS

The purpose of this study was to define cell-wall components of Staphy lococcus epidermidis responsible for activation of human polymorphonuc lear leucocytes (PMNL). Metabolic activation of PMNL was determined by chemiluminescence (CL). Purified peptidoglycan (PG) induced a concent ration-dependent metabolic burst in PMNL. The minimal concentration ne eded for CL induction was 1 mug/ml. Comparison between different S. ep idermidis strains showed variation in the capacity to induce CL in PMN L. Purified PG induced a higher CL response in PMNL than its intact pa rent strain; this effect was found in all S. epidermidis strains. Lipo teichoic acid (LTA), PG stem peptide and muramyldipeptide (MDP) did no t induce CL; teichoic acid induced a CL response only at very high con centrations. No differences in CL inducing capacity were found between PG, crude cell walls, and purified cell walls of S. epidermidis. Soni cation of PG strongly diminished CL-inducing capacity. PG treatment wi th mutanolysin immediately resulted in decreased CL-inducing capacity. Treatment of PG with S. aureus lytic enzyme (SALE) 10 mug/ml for up t o 15 min enhanced the CL response to PMNL; a similar increase in CL wa s induced by PG treated with SALE at 1 mug/ml for up to 120 min. Beyon d these times, a continuous decrease in PG-induced CL was observed. In conclusion, PG was found to be the major cell-wall component of S. ep idermidis involved in CL induction. Moreover, a minimal fragment size or a specific tertiary structure of PG, or both, is required for metab olic activation of PMNL.