In the context of Csf2r-deficient pulmonary alveolar proteinosis (PAP), first studies concentrated on bone marrow (BM)-derived MΦ, which have been transferred as a single dose directly into different mouse models, which faithfully recapitulate the clinical phenotype of PAP [13, 14]. The gene discussed is CSF2RA; the disease is pulmonary alveolar proteinosis.