Increased eosinophil cationic protein levels in bronchoalveolar lavage from wheezy infants

Although studies examining the serum suggest a role for eosinophils in whee zing episodes in infants and toddlers, the presence of a chronic eosinophil ic inflammation within their airways remains to be demonstrated. In this st udy we investigated whether eosinophil cationic protein (ECP) levels are in creased in BAL fluid (BALF) from infants and toddlers with recurrent wheezi ng episodes, during an asymptomatic period. The levels of ECP in BALF were quantitated by radioimmunoassay in 61 children (36 with severe recurrent ep isodes of wheezing and 25 who were non-wheezy), aged 6-36 months, in whom f lexible bronchoscopy was clinically indicated. BALF eosinophil counts were less than or equal to 1% in all patients and did not differ in wheezers, co mpared to non-wheezers. In contrast, ECP levels in BALF were greater than o r equal to 2.2 mug/l in 18 of 36 (50%) wheezy infants but in only three of 25 (12%) control infants (p <0.01). Neutrophil counts were significantly hi gher in the wheezer group than in the non-wheezer group (8.1x10(3) cells/ml vs. 3.0x10(3) cells/ml). ECP levels in the BALF were not correlated with t he absolute number of eosinophils (r=0.03; p = 0.8) but were correlated wit h the absolute number of neutrophils (r=0.54; p = 0.001). There was no asso ciation between high ECP levels in BALF and the atopic status of the wheeze rs. In conclusion, ECP levels are increased in BALF from young children wit h recurrent wheezing episodes, even during relatively quiescent periods, su ggesting a chronic increased cell activation in the lower airways.