showed that ILD progression in CVID correlates with increased levels of IgM, particularly with the production of IgM within B cell follicles in lung parenchyma; the main stimulator of pulmonary B cell hyperplasia seems to be BAFF, which was increased both in the blood and in the lung of CVID-ILD patients (63). The gene discussed is TNFSF13B; the disease is common variable immunodeficiency.