Inhibitory effect of disodium cromoglycate on late asthmatic response

Disodium cromoglycate (DSCG) is a widely used anti-asthmatic drug with few side effects. One of the mechanisms by which DSCG suppresses asthma is prevention of anaphylactic release of chemical mediators from mast cells. However, it has also been reported that DSCG attenuates late asthmatic response and airway hyperresponsiveness, the induction mechanisms of which can not be explained simply by release of chemical mediators from mast cells. Mechanisms of anti-inflammatory effects of DSCG other than its mast-cell stabilising effect have been unclear. In this study, we evaluated effects of DSCG on early and late asthmatic response in guinea pig. Guinea pigs were alternately sensitized and challenged by exposure to mists of ovalbumin+Al(OH)3 and ovalbumin, respectively. DSCG administered intratracheally before the fifth challenge dose-dependently inhibited late asthmatic response, but early asthmatic response was not affected. Interestingly, DSCG at 2 mg/kg potently suppressed increases in cysteinyl leukotrienes and thromboxane A2 in the lung during late asthmatic response. Eosinophilia was slightly reduced by DSCG. The inhibitory effect of DSCG on late asthmatic response is apparently due to inhibition of release of arachidonic acid metabolites.