Mast cells are cells with ubiquitous tissue distribution, derived from CD34 + multipotent hematopoietic cells. These cells play a fundamental role in the initiation of innate and adaptive immune response and in IgE-dependent allergic reactions or in various inflammatory reactions.Mastocytosis is defined as a myeloproliferative neoplastic disorder, caused by an abnormal accumulation of mast cells in one or more organ systems. Mastocytosis presents in cutaneous and systemic forms. In patients with systemic mastocytosis, the most frequent point mutation is KIT D816V, whereas in pediatric patients, where the disease is usually restricted to the skin, different KIT defects have been detected, mostly in the extracellular portion of KIT.In a primary culture of mast cells made from precursors of one cord blood, we have successfully isolated a new human mast cell line called ROSA KIT WT with a phenotype and reactivity comparable to those of normal mast cells. This cell line is dependent on SCF for growth and expresses the KIT receptor wild. It is easy to grow in large quantities, to freeze and to activate by IgE-anti IgE couple or a couple of allergen and corresponding specific IgE. This cell line can be used to study pathophysiologic mechanisms of allergy and to develop and use high-throughput screening tests of molecules in search of anti-allergic properties.In addition, we transfected these cells by lentiviral vectors providing constructs encoding the mutated KIT D816V or the mutated KIT Delta 417-419 insY, two KIT abnormalities encountered in the course of mastocytosis. This allowed us to establish two new cell lines independent of SCF for proliferation, ROSA KIT D816V and ROSA KIT Delta417-419 insY, which are particularly easy to grow in large quantities, and whose phenotype is similar to that of abnormal mast cells during mastocytosis. These two cell lines can be used for pathophysiologic studies on mastocytosis and for high throughput screening of molecules in search of antiproliferative effects specifically directed against the mutated KIT or against one or other of the intracellular molecules involved in signal transduction induced by mutant KIT.
