Establishment of a novel human basophil cell line for functional analysis and in vitro allergy testing

Basophils are the rarest granulocytes and play diverse roles, e.g., in protective immunity and allergic inflammatory reactions. However, the underlying molecules and mechanisms involved in basophil differentiation and functions, particularly in humans, remain largely unknown. This may be due to the lack of high-quality research tools. We established a novel, immortalized, human basophil cell line by introducing human papillomavirus 16-E6/E7, c-MYC, and BCL-xL gene expression systems into cultured basophils, and evaluated whether this cell line is useful as a research tool, compared with KU812, which is the most commonly-used human basophil cell line. This cell line expressed various basophil markers, including CD123, CD203c, and the high-affinity immunoglobulin (Ig)E receptor α-chain and can mature into more differentiated cells under specific culture conditions. The differentiated cells stimulated with anti-IgE antibodies showed increased CD203c expression in a dose-dependent manner, whereas the differentiated KU812 cells showed little activation after the stimulation. The established cell line also demonstrated increased sensitivity to allergic activation when stimulated with an allergen (NP-BSA) and allergen-specific IgE (anti-NP-IgE). Furthermore, histamine- and interleukin-4-releasing abilities were also confirmed. These allergic activation profiles were similar to those of basophils from healthy individuals, although the activation levels of the established cells were lower than those of basophils from highly-sensitive individuals. These findings suggest that the established basophil cell line has substantially different characteristics from a conventional cell line and could serve as a new tool for investigating basophil differentiation and functions, as well as for testing allergic reactions.