Serum eosinophilotactic activity in eosinophilic fasciitis.

Serum eosinophil chemotactic activity was determined by the Boyden chamber technique in 20 patients with eosinophilic fasciitis. Increased eosinophil chemotactic activity (greater than 125% of background) was found in all 20 patients (mean 297% +/- 129), whereas sera of 20 controls with systemic sclerosis and diffuse scleroderma had increased eosinophil chemotactic activity in only 6 (30%) instances (mean 96% +/- 47, P less than 0.001). Although serum eosinophil chemotactic activity decreased over time in all 8 eosinophilic fasciitis patients studied longitudinally, this activity returned to normal in only 3, all of whom received prolonged courses of corticosteroids. Preliminary data suggest the existence of a eosinophilotactic serum factor common to patients with eosinophilic fasciitis.