Fig. 3.

IL-6 secretion in the absence of calcium flux. a, b WT and α2-null (KO) FSMCs (1 × 10⁶) were treated with anti-DNP IgE overnight and then stimulated with DNP-HAS (a) or Listeria plus anti-Listeria antibody and serum (LAS) or ionomycin (2 μm) (b). The time course of calcium flux from 2 independent experiments is shown in each graph. c, d WT FSMCs (5 × 10⁴/well), in the presence or absence of Ca²⁺, were stimulated with either anti-DNP IgE followed by DNP-HAS (IgE + DNP) (c), Listeria plus anti-Listeria antibody (LA), or LAS (d). Cell-free supernatants were analyzed by ELISA for either β-hexosaminidase (c) or IL-6 (d) levels. The presence of Ca²⁺ was required for the release of significant amounts of β-hexosaminidase. e, f WT FSMCs were preincubated for 15 min at 37° C with the calcium chelator BAPTA or media alone and then stimulated as described for c and d. Secretion of β-hexosaminidase (e), but not IL-6 (f), was inhibited in the presence of BAPTA, as determined by ELISA on cell-free supernatants. Experiments were performed in duplicate and results are expressed as means ± SEM. p values were determined using Student's t test (* p < 0.02).