CSF2RB and pulmonary alveolar proteinosis: Here, macrophages from different stem cell sources (HSCs and induced pluripotent stem cells (iPSCs)) and species (mouse, human) were used and several studies reported significant improvement of disease parameters in Csf2rb−/−, Csf2ra−/−, as well as human IL-5/GM-CSF knock-in PAP mice after pulmonary macrophage transplantation (PMT) [22,64,65,66,67,68,69].