FIGURE 5.

Calcium mobilization is impaired in anti-insulin immature B cells upon chronic insulin encounter. Intracellular Ca²⁺ mobilization was measured. Cells were loaded with fura 2-AM. Basal fluorescence readings were taken for 45 s; arrow indicates stimulation. 125Tg (A) or IgHELMD4Tg (B) naive immature B cells (Fig. 2A) were stimulated with human insulin (solid line) or HEL (dashed line). C, Mature, anergic 125Tg spleen cells were stimulated with human insulin. 125Tg naive immature B cells were cultured with or without human insulin (0 ng/ml, black solid line; 500 ng/ml, dashed gray line; 5 × 10⁴ ng/ml, dashed black line) for 1 day and stimulated with human insulin (D), anti-IgM (E), or ionomycin (G). F, 125Tg (gray line) or IgHELMD4Tg (black line) naive immature B cells were stimulated with ionomycin. Data are representative of three or more experiments.