IDENTIFICATION OF NEUTROPHIL CHEMOTACTIC FACTORS IN BRONCHOALVEOLAR LAVAGE FLUID OF ASTHMATIC-PATIENTS

Background Although neutrophils have been implicated in bronchial asth ma, the mechanism(s) which bring these cells into the airways is poorl y understood. Objective To investigate the presence and identity of ne utrophil chemotactic factors in bronchoalveolar lavage (BAL) fluid fro m atopic asthmatic subjects. Method BAL fluid was obtained from 13 sub jects (seven asthmatics and six normals), aged 19 to 60 yr, at broncho scopy. Separation of neutrophil chemotactic activity (NCA) was achieve d by FPLC cation exchange chromatography. Fractions were collected and assayed for chemotaxis in multiwell micro-chemotaxes chambers using p olycarbonate filters, for the complement peptide C5a/C5a des Arg by ra dioimmunoassay (RIA) and for interleukin-8 (IL-8) by ELISA. Results NC A was found in FPLC fractions of BAL samples in four out of seven asth matics and each of these subjects had at least three similar peaks of NCA. The major peak of NCA was found to contain immunoreactive C5a/C5a des Arg and chemotaxis. In response to this NCA could be blocked by d esensitization of the neutrophils with recombinant C5a. Purified serum derived C5a/C5a des Arg was found to have altered chromatographic pro perties when added to BAL fluid; this suggested that BAL fluid contain ed proteins which interacted with the C5a/C5a des Arg. Immunoreactive IL-8 (iIL-8) was also detected but its concentration or chemical form was insufficient to induce neutrophil chemotaxis. Conclusion This stud y demonstrates that bronchial asthmatic lavage fluid contains C5a/C5a des/Arg and IL-8, together with other as yet unidentified factors whic h may contribute to neutrophil recruitment in this disease.