In adults, intense staphylococcal skin colonization and hyperactivity of polymorphonuclear leukocyte (PMN) oxidative metabolism are characteristic features of atopic dermatitis. Precise data on childhood atopic dermatitis are lacking. In a prospective study we analysed the PMN chemiluminescence activity with special reference to staphylococcal stimuli in 19 children (mean age 6.2 years) with mild to moderate atopic dermatitis. Staphylococcus aureus was isolated from 17/19 (90%) of children with atopic dermatitis and 13/45 (29%) of healthy age-matched controls (p less than 0.001). The mean (SEM) chemiluminescence activity of unstimulated atopic dermatitis-PMN was 0.34 (0.009) (controls: 0.092 (0.003) x 10(6) cpm/10(6) PMN/min (p less than 0.02). Staphylococcal antigens (S. aureus, S. epidermidis, S. haemolyticus) induced a 1.9-3.1-fold higher peak chemiluminescence response in children with atopic dermatitis than in controls (p less than 0.05). The time interval until peak chemiluminescence activity was considerably shorter for all stimuli in atopic dermatitis. We conclude that PMN of children with atopic dermatitis are "primed", showing enhanced release of reactive oxygen metabolites even in the "resting" state, and are easily stimulated by staphylococcal antigens present on the skin of patients with atopic dermatitis from early childhood on. We speculate that PMN hyperreactivity may contribute to chronic skin damage in atopic dermatitis.