The effects of Haemophilus influenzae vaccination on anaphylactic mediator release and isoprenaline-induced inhibition of mediator release.

The influence of Haemophilus influenzae on anaphylactic mediator release from ovalbumin-sensitized isolated guinea pig lungs was investigated. Lungs from H. influenzae-vaccinated animals released prostaglandins and thromboxanes following a smaller dose of ovalbumin than was effective in non-vaccinated animals. Histamine release was significantly increased in 4 day-vaccinated animals but not 1 or 10 days after vaccination, while broncho-constriction was potentiated in 1 and in 4 day-vaccinated animals. This increased histamine release was achieved following 2 micrograms ovalbumin. In contrast, doses of 10 micrograms and 1 mg ovalbumin respectively did not affect and decreased histamine release in the vaccinated group. The inhibition of anaphylactic mediator release by an infusion of 6 x 10(-9) M isoprenaline was significantly attenuated by H. influenzae vaccination. These results indicate an increased sensitivity to antigenic challenge and suggest that the functioning of beta-adrenoceptors was decreased as a result of H. influenzae vaccination.