ANALYSIS OF INFLAMMATORY REACTIONS OBSERVED IN BRONCHOALVEOLAR LAVAGES (BALS)

Immunological toxicities associated with immune checkpoint inhibitor (ICI) monoclonal antibodies are unpredictable autoimmune and inflammatory pathologies that can affect all treated patients. Some of these events are severe and occur in 15-20% of patients treated with Programmed Death 1 (PD-1) antibodies. The study of cellular immunological characteristics within tissues affected by toxicities and the interactions between the different actors of these toxicities aims at improving the knowledge concerning the mechanisms of these toxicities, but also at being able to specify the unexpected effects of ICIs on cells of the immune system, outside the tumor microenvironment. Diffuse infiltrative lung disease is one of the most frequent and severe toxicities encountered in patients treated with anti PD-(L)1; either for bronchial cancer, melanoma or any other type of cancer. Patients developing this type of complication benefit from cytological, bacteriological, mycological and molecular analyses of intra-alveolar constituents obtained by bronchoalveolar lavage (BAL) performed during bronchial fibroscopy as part of their routine care. These analyses help to confirm the diagnosis of alveolitis, to specify the cellular characteristics of alveolar inflammation and to eliminate differential diagnoses of ICI toxicity.