Effect of sodium cromoglycate and nedocromil sodium on anti-IgE-induced and anti-IgG4-induced basophil degranulation.

Both anti-IgE and anti-IgG4 induce human basophil degranulation as assessed by toluidine blue staining. Anti-IgG4 has been recently shown to act on the human basophil by a 2-step process: anti-IgG4 induces the release from eosinophils of eosinophil cationic proteins which in turn induce human basophil degranulation. In the present study, we show that sodium cromoglycate and nedocromil sodium have no direct effect on human basophil degranulation but inhibit the anti-IgG4-induced degranulation. This effect was dose-dependent and significant inhibitions were obtained at 2.5 to 25 mumol/L for sodium cromoglycate and 25 mumol/L for nedocromil sodium. No drug effect was observed on the basophil degranulation induced by supernatants from anti-IgG4-stimulated eosinophils. However, the release of basophil degranulating factors (eosinophil cationic proteins) by anti-IgG4 from purified eosinophils was significantly inhibited after preincubation with 25 mumol/L of sodium cromoglycate or nedocromil sodium. Taken together, these results indicate that both sodium cromoglycate and nedocromil sodium have an inhibitory effect on the first step of anti-IgG4-induced human basophil degranulation, thus strongly suggesting that these drugs inhibit the release of eosinophil cationic proteins from human eosinophils.