Elevated mononuclear leukocyte phosphodiesterase in allergic dogs with and without airway hyperresponsiveness

To investigate if mononuclear leukocyte beta-adrenergic hyporesponsiveness of Basenji greyhound (BG) dogs is associated with atopy or nonspecific airway hyperresponsiveness, we examined the relationship between mononuclear leukocyte cAMP phosphodiesterase levels, airway responsiveness to methacholine, and intradermal allergen responses in 17 BG dogs, five unrelated purebred Basenjis, and five greyhounds. BG dogs were hyperresponsive to aerosols of methacholine compared to Basenjis and greyhounds. Both BG dogs and Basenjis were allergic and had increased leukocyte cAMP phosphodiesterase activity compared to greyhounds. We concluded that the leukocyte abnormality is not associated with airway hyperresponsiveness. The leukocyte abnormality is either associated with the allergic state, with some hereditary trait that BG dogs acquired from the Basenji ancestry, or the leukocyte abnormality is necessary but not sufficient for the development of airway hyperresponsiveness.