Effect of a platelet release fraction on glycosaminoglycan synthesis by cultured dermal fibroblasts from patients with progressive systemic sclerosis

Confluent cultures of dermal fibroblasts from patients with progressive systemic sclerosis (PSS) and healthy controls were investigated for the synthesis of glycosaminoglycans (GAG) in response to a platelet release fraction (PRF) obtained by treatment of pooled platelets from normal individuals with adenosine 5'-diphosphate (ADP). PRF, at concentrations of 1 to 50 micrograms protein/ml, produced a linear increase in GAG synthesis that was always greater in cultures of PSS fibroblasts than in cultures of normal fibroblasts (P less than 0.001). A partial inhibition of GAG synthesis was observed with 100 micrograms/ml of PRF. The increased GAG synthesis in cultures incubated with PRF was not due to ADP. These findings demonstrate a difference in response to PRF between PSS and normal fibroblasts and may reflect an increased responsiveness of PSS fibroblasts to platelet factors.