FREE AND COMPLEXED INTERLEUKIN-8 IN BLOOD AND BRONCHIAL-MUCOSA IN ASTHMA

We have tested the hypothesis that the expression of interleukin-8 (IL -8) is increased in bronchial tissue and circulating leukocytes of ato pic asthmatics, indicating a role for this chemokine in asthma. The co ncentration of IL-8 in its free form and complexed with IgG or IgA was measured by ELISA in bronchial tissue, serum, and lysates of freshly isolated peripheral blood mononuclear cells and granulocytes from subj ects with mild or severe asthma and nonatopic nonasthmatic subjects. S erum ECP was measured by fluorescent enzyme immunoassay. Free IL-8 was detected in the sera (n = 44) and bronchial tissue (n = 9) of all sub jects with severe atopic asthma, but it was undetectable in normal sub jects and subjects with mild atopic asthma, suggesting that free IL-8 is a marker of severe asthma. A positive correlation between free IL-8 and serum ECP levels found in severe disease suggests that IL-8 is as sociated with eosinophil activation. Complexes of IL-8 with IgA and Ig G were detected in all serum and tissue samples. However, the levels o f the IL-8-IgA complex were increased in the bronchial mucosa in asthm a, and in blood were related to disease activity. Together, these resu lts point to upregulation of IL-8 production in asthma and the inducti on of IL-8 binding immunoglobulins of the IgA class in the inflamed mu cosa. We suggest a proinflammatory role for these complexes in lung ti ssue.