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 D₂, thromboxane A₂, 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.