POLYMORPHONUCLEAR NEUTROPHILS RELEASE S-35 LABELED PROTEOGLYCANS INTO CARTILAGE DURING FRUSTRATED PHAGOCYTOSIS

Rabbit peritoneal polymorphonuclear neutrophils (PMN), incubated in medium containing [S-35]sulphate, incorporated S-35 into proteoglycan and protein fractions. Approximately 46% of the S-35-labelled macromolecules associated with the PMN cells after 1 h of incubation were recovered in a cytoplasmic granule extract, the majority being present in azurophil granules. Analysis of the azurophil granule fraction showed that approximately 90% of the S-35-labeIled macromolecules were proteoglycans. When challenged with heat-aggregated rabbit gamma-globulin in the presence of cytochalasin B and cGMP, PMN were induced to release granular enzymes but did not release S-35-labelled proteoglycans into the incubation medium. When incubated with articular cartilage slices, PMN released their granule S-35-labelled proteoglycan into the medium and into the cartilage matrix. Granule enzymes and S-35-labelled granule proteoglycan were extracted from the cartilage tissue after incubation and S-35-labelled macromolecules were detected in the cartilage tissue by autoradiography.