Eosinophil cationic protein, myeloperoxidase and tryptase in children with asthma and atopic dermatitis

Serum levels of eosinophil cationic protein (ECP), myeloperoxidase (MPO), tryptase, total IgE and differential blood cell counts were studied in atopic children with: 1) moderate to severe asthma using inhaled steroids and symptom-free for the last 3 weeks (n= 13), 2) mild asthma with sporadic symptoms, using only inhaled β₂-agonists < 3 times/week (n= 15), 3) acute asthmatic attacks admitted to hospital (n= 12), 4) mild to moderate atopic dermatitis (n= 14). Fifteen children without any history of atopy served as controls. ECP, MPO, tryptase and IgE were measured in serum by radioimmunoassays (RIA). The symptom-free children with inhaled steroids had similar median ECP and MPO values as the controls, 8.0 and 360 μg/l, vs. 9.0 and 310 μg/l, while both ECP and MPO were significantly (p < 0.001) increased in the symptom-free children without anti-inflammatory treatment, 32 and 887 μg/l and in those with acute asthma, 28 and 860 μg/l. The children with atopic dermatitis had increased ECP but normal MPO levels, 16.0 and 455 μg/l. Tryptase in serum was not measurable in any patient. All groups except the control group had significantly elevated total IgE levels. The results indicate that in atopic children serum ECP is a good marker of ongoing asthma or atopic dermatitis. The normal levels of ECP and MPO in the children with asthma using inhaled steroids seem to reflect successful anti-inflammatory treatment. The increased levels of ECP and MPO in the children with mild asthma and no anti-inflammatory treatment may indirectly reflect airway inflammation.