Increased antigen-induced local and systemic mediator release in rhinitis subjects with pulmonary symptoms in the pollen season.

In order to delineate parameters that might discriminate between allergic subjects who develop R or R-P symptoms during natural antigen exposure, 26 subjects allergic to grass or ragweed pollen were classified into R or R-P groups, and then the antigen sensitivity and degree of in vivo mediator release were compared. Antigen-skin sensitivity was quantitated by dilutional skin-test titration, and bronchial sensitivity was quantitated by the amount of inhaled antigen required to receive the FEV1 by 20%. Mediator release was determined by measuring the amount of histamine that was released into skin chambers during antigen incubation and the rise in plasma histamine and serum NCA during antigen-induced bronchospasm. Compared to the 13 R subjects, the 13 R-P subjects were: (1) more sensitive to antigen by both skin-test and inhalation challenge, (2) responded to inhalation of antigen with a greater fall in FEV1 and a greater rise in serum NCA and plasma histamine, and (3) released more histamine into skin chambers after antigen incubation. Even when R and R-P subjects were matched by comparing only subjects with equal skin sensitivity to antigen, greater increases in serum NCA and plasma histamine occurred after inhalation of antigen in the R-P subjects. These data are consistent with the hypothesis that allergic rhinitis subjects who develop pulmonary symptoms during natural pollen exposure are more sensitive to antigen and release more mediators in response to antigen administration. It is therefore possible that the degree of mediator release may be an important factor in determining the pattern of clinical responses to antigen exposure.