Response to corticosteroids in the hypereosinophilic syndrome. Association with increased serum IgE levels.

Severe blood eosinophilia (16,500/cu mm and 6,500/cu mm) accompanied by involvement of the lungs, pleura, heart, pericardium, liver, gastrointestinal tract, peripheral nerves, or skin developed in two patients with bronchial asthma. Associated with the eosinophilia were elevated serum IgE levels (1,400 IU/ml and 10,500 IU/ml), depressed serum C4 complement levels (13 mg/100 ml and 6 mg/100 ml), and high titers of rheumatoid factor (1:2560 and 1:640). Symptoms improved after treatment with prednisone and the eosinophil counts and serum IgE and C4 complement levels returned to normal.