MCL1 increases primitive thymocyte viability in female mice and promotes thymic expansion into adulthood.

Increasing the pool of cells at early T-cell developmental stages enhances thymopoiesis and is especially beneficial when T-cell production is compromised by radiation or aging. Within the immature double-negative (DN; CD4(-)CD8(-)) thymocyte subpopulation, the DN1 subset contains the most primitive cells including the rare early T-cell progenitors (ETPs). In the present study, a human MCL1 transgene, under the control of its endogenous promoter, resulted in enlargement of an undistorted thymus in C57/BL6 mice.