Role of C-type lectin receptor CLEC12A in human basophil activation (48.6)

CLEC12A is a member of the C-type lectin receptor family with a cytoplasmic immunoreceptor tyrosine-based inhibitory motif. Murine CLEC12A is expressed on variety of cell types including dendritic cells, monocytes/macrophages, B cells, neutrophils and basophils but not NK cells. In humans, CLEC12A is reported to be expressed on dendritic cells (DC, both myeloid and plasmacytoid), monocytes, B cells (normal and leukemic) and NK cells, but not on T cells or basophils. Performing flow cytometric analysis of human peripheral blood leukocytes using an anti-human CLEC12A antibody (clone 50C1), we report CLEC12A expression on a subset of CD3, CD19 and CD56 negative cells. Further analysis revealed these cells to be CCR3+ basophils. Antibody mediated ligation of CLEC12A on DCs results in cytokine production and cellular maturation and can inhibit NK cell mediated cytotoxicity. In response to IgE and IL-3, basophils can induce Th2 differentiation and amphiregulin production, respectively. We hypothesize that ligation with CLEC12A will alter IL-3 and/or IgE mediated basophil activation, which will be studied in our ongoing work.