Characterization of a novel human mast cell line that responds to stem cell factor and expresses functional FcεRI.

Abstract

Studies of human mast cells (MCs) are constrained by the paucity of functional cell lines, the expense of maintaining MCs in culture, and technical complexities. We derived and characterized a human MC line that arose spontaneously from a culture of nontransformed hematopoietic progenitor cells. CD34(+) enriched mononuclear cells derived from a donor with aspirin-exacerbated respiratory disease were cultured for 8 weeks with stem cell factor and IL-6 and with IL-3 for the first week only. The cells (termed LUVA cells) survived and proliferated without further addition of any growth factors and have been maintained in culture for approximately 2 years. LUVA cells possess metachromatic cytoplasmic granules that are immunoreactive for tryptase, cathepsin G, and carboxypeptidase A3. They express transcripts encoding FcεRI, c-kit, chymase, tryptase, histidine decarboxylase, carboxypeptidase A3, and the type 1 receptor for cysteinyl leukotrienes. Flow cytometry confirmed uniform expression of FcεRI, c-kit, and FcγRII. FcεRI cross-linkage induced the release of β-hexosaminidase, prostaglandin D(2), thromboxane A(2), and macrophage inflammatory protein 1β. Immortalization was not associated with either a known genomic mutation of c-kit in the donor or a somatic mutation of c-kit within the cells, and it was not associated with c-kit autophosphorylation. LUVA cells are an immortalized human MC line that can be maintained without stem cell factor and display high levels of normally signaling c-kit and FcεRI. These cells will prove valuable for functional human MC studies.