Increased IgG antibody-induced cytotoxicity against airway epithelial cells in patients with nonallergic asthma.

Background: IgG autoantibodies to airway epithelial cell proteins have been detected in patients with nonallergic asthma.
Objective and Methods: To evaluate the functional significance of these autoantibodies, we examined the presence of IgG antibody-induced cytotoxicity against airway epithelial cells (A549) by the microcytotoxicity assay using IgG antibodies purified from patients with nonallergic asthma.
Results: IgG antibody-induced cytotoxicity (expressed as percent cell lysis) was significantly increased in nine patients with nonallergic asthma (mean +/- standard deviation; 30.6 +/- 7.3%) as compared with eight healthy controls (13.9 +/- 5.1%) and nine patients with allergic asthma (20.3 +/- 10.4%; p < 0.05). In addition, IgG antibody-induced cytotoxicity was significantly inhibited when IgG antibodies from patients with nonallergic asthma were pre-incubated with recombinant human airway epithelial cell autoantigens (cytokeratin 18 or alpha-enolase proteins; p < 0.05).
Conclusion: These results suggest a possible involvement of IgG autoantibody-induced cytotoxicity against airway epithelial cells in the pathogenesis of nonallergic asthma.