International Journal of Cell Cloning, Vol 5, 108-121, Copyright © 1987 by AlphaMed Press
Differentiation and transdifferentiation of mast cells; a unique member of the hematopoietic cell family
Y Kitamura, Y Kanakura, J Fujita and T Nakano
Information about the differentiation of mast cells has increased
remarkably in the past ten years. This progress has resulted from the
introduction of techniques which developed in other fields of experimental
hematology. Once mast cells were recognized as a progeny of multipotential
hematopoietic stem cells, their unique differentiation processes were
clarified. Although most of the progeny of stem cells leave the
hematopoietic tissue after maturation, undifferentiated precursors of mast
cells leave the hematopoietic tissue. Morphologically, unidentifiable
precursors migrate in the bloodstream, invade the connective tissues or the
mucosa of the alimentary canal, proliferate, and differentiate into mast
cells. Even after their morphological differentiation, some mast cells
retain an extensive proliferative potential. There are at least two
subpopulations of mast cells: a connective-tissue type and a mucosal type.
Connective tissue-type and mucosal mast cells can be distinguished by
histochemical, electron microscopical, biochemical and immunological
criteria; however, these two types can interchange, and their phenotypes
are determined by the anatomical microenvironment in which their final
differentiation occurs. Although biochemical natures of the anatomical
microenvironment are unknown, molecules that support proliferation and
differentiation of mast cells in vitro have been characterized, i.e.,
interleukin 3 and interleukin 4. In the next ten years, increased
information about the differentiation processes will probably induce
further understanding of mast cell functions.
