Effect of histamine antagonists and agonists on IgE production in mice.

This study was undertaken to investigate the effect of histamine, its receptor antagonists and agonists on IgE antibody production in mice. BALB/c mice were immunized intraperitoneally with 1 mg alum plus 30 micrograms of Ag90, the antigen of Japanese occupational asthma. Histamine receptor antagonists were administered before the immunization and simultaneous injection of histamine. The mice were bled 14 days after immunization and anti-Ag90 IgE antibody was obtained. Titers of the antisera were measured by passive cutaneous anaphylaxis reaction in Sprague-Dawley rats. Treatment with histamine only did not affect the level of specific IgE antibody. Administration of H1 antagonist or H2 agonist suppressed IgE production significantly. In contrast, treatment with H2 antagonist or H1 agonist augmented the IgE antibody production. Injection of H1 + H2 antagonists had no effect on the antibody production. These results suggest that histamine suppressed specific IgE production via H2 receptors and enhanced it through H1 receptors in the induction phase of the system.