FIGURE 4.

Mediator release of humanized RBL-SX38 by α-Gal. RBL-SX38 cells providing the human FcϵRI were sensitized with the scFv-IgE, IgE, and TNP-specific mouse IgE C38-2 as control (A). Antigen-independent degranulation was induced by the addition of anti-human IgE and anti-murine IgE, respectively (A). Antigen-dependent degranulation was induced by the addition of different α-Gal-carrying proteins, including biotinylated thyroglobulin immobilized to streptavidin-coated beads, and by the addition of TNP-labeled BSA for the control (B). Degranulation was monitored by β-hexosaminidase activity released into culture supernatants. Data are mean ± S.D. (error bars) of triplicate measurements.