Evaluation of cell-surface IgE receptors on the canine mastocytoma cell line C2 maintained in continuous culture

Objective—To assess expression and function of cellsurface IgE receptors on the canine mastocytoma cell line C2 maintained in continuous culture. Sample Population—C2 cells maintained in medium lacking IgE for up to 10 passages before being stored at –80 C. Procedure—Cells were thawed, cultured in medium without IgE for 1 to 3 passages, sensitized for 7 days with IgE-rich serum from dogs naturally sensitized to Ascaris suum, and stimulated with antigen Asc S1 from A suum, goat polyclonal anti-canine IgE, or calcium ionophore and phorbol myristate acetate (PMA). Percentage of intracellular β-hexosaminidase released and concentration of tumor necrosis factor-α (TNF-α) synthesized after stimulation were determined. Expression of cell-surface IgE receptors was assessed by use of a flow cytometry. Results—Immunologic stimulation (antigen or anti-IgE) failed to induce release or synthesis of detectable amounts of β-hexosaminidase or TNF-α. In contrast, nonimmunologic stimulation (calcium ionophore and PMA) led ...