NEW research suggests that early impairment in mucosal IgA immunity may contribute to the later development of bronchiolitis obliterans syndrome (BOS) in lung transplant recipients, providing potential markers for early detection.
Bronchiolitis obliterans syndrome remains a leading cause of long-term graft failure following lung transplantation (LuTx), often triggered by infections that compromise airway immunity. As IgA plays a critical role in mucosal defence, researchers retrospectively studied whether deficiencies in IgA-mediated immunity were associated with BOS onset. The study included 60 stable LuTx recipients from the COLT cohort, half of whom developed BOS by 3.5 years post-transplant. Bronchoalveolar lavage fluid (BALF) and serum samples collected pre-transplant, and at 6 and 12 months post-transplant, were analysed for secretory IgA (S-IgA), monomeric IgA, secretory component, and cytokines. Tissue samples from 54 additional patients at various BOS stages were also evaluated for polymeric Ig receptor (pIgR) expression and subepithelial IgA-producing B-cell presence.
S-IgA levels in BALF significantly declined between 6–12 months post-transplant (p=0.0001), with levels at 12 months notably lower in patients who later developed BOS (p=0.0018). Patients with reduced BALF S-IgA were more susceptible to infections. Conversely, serum SC levels were elevated in patients with BOS (p<0.01), and both low S-IgA and high SC were associated with increased BOS risk. Tissue analysis revealed that pIgR expression in bronchiolar epithelium decreased progressively with BOS severity (p=0.0001), supporting the link between impaired IgA transport and disease progression.
These findings highlight a measurable early disruption in IgA-mediated mucosal immunity in LuTx recipients who later develop BOS. Monitoring S-IgA and secretory component levels, along with pIgR expression, may offer clinicians valuable tools for identifying patients at higher risk and guiding earlier interventions.
Reference
Carlier FM et al; COLT Consortium. Impaired IgA Mucosal Immunity Following Lung Transplantation: A Potential Trigger for Bronchiolitis Obliterans Syndrome. Eur Respir J. 2025; DOI: 10.1183/13993003.02212-2024.
