Double expression of CD34 and CD117 on bone marrow progenitors is a hallmark of the development of functional mast cell of Callithrix jacchus (common marmoset)

Mast cells (MCs) are developed from hematopoietic progenitor cells and play an important role in inflammation. Study of the kinetics of development and accumulation of primate MC in vivo is crucial for the control of human inflammatory diseases, as evolution of the immune system is quite rapid and inflammation including MC response is considered to be different between mouse and human. In the present study, we examined the development of MC from hematopoietic progenitors of Callithrix jacchus (common marmoset), an experimental animal of nonhuman primates. Bone marrow cells were fractionated for the expression of CD34 and CD117 by cell sorting. MCs were developed in vitro or by transplanting the cells to NOD/SCID/IL-2γc knockout (NOG) mice. In vitro culture of CD34⁺CD117⁺ (double positive, DP) cells with stem cell factor could generate high-affinity Fc epsilon receptor (FcεR)-expressing CD117⁺ cells with typical granules. The developed MC released β-hexosaminidase and produced leukotriene C₄ after the stimulation of FcεRI. Transplantation of DP cells gave rise to a marked expansion of CD34^-CD45⁺CD117⁺FcεR⁺ cells in NOG mice. They expressed transcripts encoding chymase 1 and tryptase β. Differentiation of CD34^-CD117⁺ cells to MCs was relatively limited compared with the DP cells, similarly to human MCs. These results suggest that this marmoset system provides a good model for human MC development.