Autoantibodies to lipids in bronchoalveolar lavage fluid of patients with acute respiratory distress syndrome

Objective: To investigate the presence of autoantibodies to lipids in the b ronchoalveolar lavage (BAL) fluid from adult patients with acute respirator y distress syndrome (ARDS). Design: Analysis of immunoglobulin G (IgG) in BAL fluid by electrophoresis followed by immunoblotting and characterization of immunoglobulins as antil ipid autoantibodies. Setting: Intensive care unit of a university hospital and two research univ ersity laboratories. Subjects: Twenty-seven mechanically ventilated patients in total, including nine patients with ARDS and two control groups. Interventions: Patients were ventilated with a mechanical ventilation mode. Six aliquots of 20-mL sterile normal saline at 37 degreesC were infused th rough the working channel of the bronchoscope. Measurements: Total protein, detection of IgG by electrophoresis followed b y immunoblotting, and characterization of IgG by enzyme-linked immunosorben t assay using different lipids as target antigens. Main Results: Antiphospholipid autoantibodies are present in BAL fluid of A RDS patients. Among the phospholipids tested, phosphatidic acid and phospha tidylserine gave the most significant activity. The IgG fraction, purified from BAL fluids by affinity chromatography, gave the same pattern of bindin g as that of the BAL fluid. Conclusion: The presence of anti phospholipid autoantibodies in BAL fluid s uggests involvement of autoimmune mechanisms in the pathogenesis of ARDS.