Bcl-2 and Bcl-XL are indispensable for the late phase of mast cell development from mouse embryonic stem cells

ObjectiveThe aim of this study was to determine the importance of the prosurvival factors Bcl-2 and Bcl-XL for mast cell development and survival.Methodsbcl-x−/− and bcl-2−/− mouse embryonic stem cells were maintained in medium supplemented with either interleukin (IL)-3 or IL-3 in combination with stem cell factor (SCF) to favor mast cell development. The development of Bcl-2 family deficient embryonic stem cell-derived mast cells (ESMCs) was monitored and Bcl-2 family gene expression and cell numbers were analyzed.ResultsDeficiency in either bcl-x or bcl-2 totally inhibited the development of ESMCs when IL-3 alone was used as a mast cell growth factor. Intriguingly, when IL-3 was used in combination with SCF, the ESMCs developed normally the first 2 weeks but thereafter the cell numbers dropped drastically. The remaining ESMCs express mouse mast cell protease 1, suggesting a mucosal-like phenotype. ESMCs lacking bcl-x or bcl-2 exhibited strong expression of A1, another prosurvival Bcl-2 family member.ConclusionFor the first time we provide direct evidence that both bcl-x and bcl-2 are indispensable for mast cell survival during the late phase of their development.