Connective tissue activation. XV. Stimulation of glycosaminoglycan and DNA synthesis by a polymorphonuclear leukocyte factor.

Human synovial fibroblasts in culture have been stimulated to augment hyaluronate synthesis and glucose utilization by connective tissue activating peptides (CTAP) extracted from human spleen, lymphocytes, platelets, granulocytes, and tumour cells. The platelet-derived mediator CTAP-III also stimulated DNA synthesis in synovial fibroblasts, but CTAP-I from lymphocytes and spleen did not. The present study demonstrates the mitogenic potential of a granulocyte mediator (CTAP-PMN). Normal granulocytes were prepared with Ficoll-diatrizoate gradients, platelet contamination being estimated by phase microscopy and by radioimmunoassay for the platelet-specific protein, beta-thromboglobulin. CTAP-PMN preparations derived from 4 x 10(7) cells/ml stimulated culture 3H-thymidine incorporation to 3.56 +/- 1.32 (SD) times control levels. Although exposure of preparations to thiols reduced their mitogenicity, CTAP-PMN was relatively heat-stable. SDS gel electrophoresis of active fractions suggested a molecular weight between 12,700 and 15,700 daltons. In double immunodiffusion, antisera to CTAP-III showed no reactivity with CTAP-PMN. CTAP-PMN or other granulocyte factors capable of stimulating fibroblast DNA synthesis may play a role in chronic proliferative synovitis or in other settings where exudative inflammation is accompanied by connective tissue growth.