Anti-interleukin 8 autoantibody: interleukin 8 immune complexes visualized by laser confocal microscopy in injured lung: Colocalization with FcγRIIa in lung tissue from acute respiratory distress syndrome patients

•Context.-Anti-interleukin 8 autoantibody:interleukin 8 (anti-lL-8 autoantibody:lL-8) complexes are present in lung fluids of patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS), and levels of these complexes correlate with progression to and the outcome of ARDS. FcyRlla, an immunoglobulin G (IgG) receptor, mediates proinflammatory activity of the complexes. Objective.-To evaluate lung tissues from patients with ARDS for presence of anti-lL-8 autoantibody:lL-8 complexes and to establish whether the complexes associate with FcyRlla. Design.-Lung tissue sections from 3 patients with ARDS and sections of normal lung tissues from 3 patients were stained with antibodies against IL-8 and IgG to detect immune complexes and with antibody against FcγRlla. In some experiments, sections were blocked with anti-Fcγ-Rlla antibody before staining. Samples were analyzed using confocal microscopy. Results.-Interleukin 8 costained with IgG and FcγRlla in lung tissues from patients with ARDS but not in control tissues, suggesting that anti-lL-8 autoantibody:lL-8 complexes are deposited in lungs of patients with ARDS via FcγRlla. Further, colocalization between IL-8 and FcγRlla could be blocked by anti-FcγRlla. Conclusions.-Our data demonstrate that anti-lL-8 autoantibody:lL-8 complexes are present in lung tissues of patients with ARDS, and are attached to FcγRlla.