An observational study involving 50 patients with APECED - a genetic autoimmune disorder - has demonstrated that targeting T and B cell activity combats a serious lung-related complication often overlooked or misdiagnosed in patients with the condition. The findings highlight a possible therapeutic route to improve lung function and quality of life for those with the disease. APECED is caused by mutations in the AIRE gene, which lead to abnormal T and B cell function, damaging internal organs. Although researchers suspect that APECED can cause other symptoms besides organ damage, the precise symptoms, as well as whether they can be treated, remains unclear. Here, Elise Ferré and colleagues investigated 50 patients with APECED in a three-year analysis. The researchers tested the patients' lung function, performed CT imaging, and analyzed immune cells from blood and lung biopsies. Surprisingly, they found that 40% of the patients had developed pneumonitis - inflammation of lung tissue - which had previously been misdiagnosed or missed, and in some cases caused severe lung infections and death. The authors also observed that patients harbored high levels of active immune cells in their airways, and detected similar abnormalities in 13 patients with thymoma and 19 patients with RAG deficiency, two other immunodeficiencies. Importantly, treating five patients with APECED with a combination of drugs that modulate T cells and B cells resolved pneumonitis and chronic cough and improved lung function after six months. Future studies should assess the treatment's efficacy and durability in larger patient groups, Ferré et al. say.