C-kit and Mastocytosis

Mast cells (MC) are tissue elements derived from a subset of hematopoietic stem cells expressing CD34, c-kit and CD13 antigens [1] (Fig. 20.1). Immature MC progenitors circulate in the bloodstream then differentiate in tissues under the influence of cytokines, one of utmost importance being stem cell factor (SCF). SCF receptor is encoded by the protooncogene c-kit, belonging to type III receptor tyrosine kinase subfamily [2] (Fig. 20.2). Ligation of the c-kit receptor by SCF induces its dimerization followed by its transphosphorylation leading to the recruitment and activation of various intracytoplasmic substrates. These activated substrates induce multiple intracellular signaling pathways responsible for cell proliferation and activation [2] (Fig. 20.3).