Stimulation of fibroblast biosynthetic activity by serum of patients with pretibial myxedema

Skin fibroblasts from the shoulder and lower extremities of normal individuals, as well as from patients with pretibial myxedema (PTM) were grown in culture. When cells reached the monolayer stage, they were labeled with ³H-glucosamine and tested for hyaluronic acid synthesis in the presence of either serum from PTM patients or normal human serum. All the fibroblasts from the pretibial area synthesized 2 to 3 times more hyaluronic acid when incubated with PTM sera than when incubated in normal human serum. Fibroblasts cultured from skin of the back or prepuce did not respond to PTM sera. This heat-stable, protease-sensitive, and dialyzable, fibroblast-stimulating factor is not a 7 Sγ-globulin. The enhanced sensitivity to PTM sera exhibited by fibroblasts from the lower extremities may explain why the lesions in this disease are restricted primarily to that area.