Proteoglycans synthesized by human polymorphonuclear leucocytes in vitro

Abstract

Polymorphonuclear leucocytes (PMN) were assessed in vitro for their ability to synthesize and secrete proteoglycans. The PMN were isolated from human peripheral blood and were found to contain less than 5% mononuclear cells. Following 24 h incubation in the presence of (35S)-sulfate, significant quantities of 35S-labelled macromolecules were detected both within the culture medium and cells. Although the PMN preparations contained some platelets (approximately five platelets:one PMN), culture of platelets alone did not result in the detection of any 35S-labelled macromolecules in either the medium or platelets. 35S/3H-labelled macromolecules from the PMN cultures were identified as proteoglycans on the basis of their degradation by papain, alkaline sodium borohydride, chondroitinase ACII, chondroitinase ABC and nitrous acid. The labelled proteoglycans isolated from the medium and cells eluted from Sepharose CL-4B with a Kav of 0.63; this indicated a small size compared with many other proteoglycans. The glycosaminoglycans associated with the proteoglycans were identified as heparan sulfate, chondroitin sulfate and dermatan sulfate, with chondroitin sulfate being the principal component. The average molecular weight of the glycosaminoglycans was determined to be 16,000. Therefore, the data from this study demonstrate the ability of human PMN to synthesize and secrete proteoglycans in vitro which appear to differ from those synthesized by mesenchymal cells with respect to molecular size and glycosaminoglycan composition.