Membrane IgE and adenyl cyclase activity in the dynamics of bronchospasm. Ketotifen as a blocker of antigen action.

A continuous exposition to antigen provokes an increase of IgE synthesis in individuals sensitized to that antigen. This increase in the synthesis is hardly seen to be reflected in seric levels; however, it is clearly seen in the quantity of IgE associated with membranes as this value increases considerably. This fact is due to the characteristic of IgE which tends to fix itself to basophil membrane. On the other hand, although no difference exists in basal adenyl cyclase activity of asthmatic and healthy individuals, the sensitivity of this enzyme to isoproterenol (beta-agonist) is greater in healthy than in asthmatic individuals. The antigenic stimulus makes adenyl cyclase activity descend in these individuals; this does not happen when the cells are treated with ketotifen before stimulating them with the antigen.