Some alterations of the leucocyte beta2-adrenoceptor/cAMP-system in patients with seasonal allergic rhinoconjunctivitis are related to disease activity.
BACKGROUND
Disturbances of beta2-adrenoceptors are discussed as a pathogenic factor in atopic diseases.


METHODS
In this study the expression and function of beta2-adrenoceptors on peripheral blood leucocytes (PBL) of seven atopic patients with seasonal rhinoconjunctivitis and their seven healthy controls was evaluated in relation to disease activity. Earlier reported data during pollen season were now compared with data obtained from the same subjects after their allergic symptoms had subsided.


RESULTS
The variables that had indicated a beta2-adrenoceptor subsensitivity in the patients during pollen season returned to control values, i.e. the reduced beta2-adrenoceptor affinity, the reduced beta2-adrenoceptor sensitivity, the reduced increase of intracellular cyclic adenosine monophosphate (cAMP) content upon stimulation with isoproterenol, and the reduced cAMP plasma concentration (values no longer significantly different from those of controls). However, the variable that had suggested an increase in activity of the cAMP degrading enzyme phosphodiesterase (PDE), i.e. the reduced basal intracellular cAMP content of the patients, remained reduced after the pollen season (4.9 +/- 1.1 pmol/10(6) cells in patients vs 8.2 +/- 0.9 pmol/10(6) cells in controls: P<0.05). There were no significant differences in beta2-adrenoceptor density between patients and controls at both investigations.


CONCLUSIONS
Atopic seasonal rhinoconjunctivitis is associated with various alterations in the PBL beta2-adrenoceptor/cAMP system that depend on disease activity. The reversible beta2-adrenoceptor subsensitivity is likely to be a consequence of the disease, whereas the irreversibly decreased basal intracellular cAMP content, suggested an elevated PDE activity, might be a basic trait of atopy.
Haen
E
E
Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität, München, Germany.
Bleise
U
U
Przybilla
B
B
D000328:Adult; D000242:Cyclic AMP / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D008875:Middle Aged; D018343:Receptors, Adrenergic, beta-2 / Q000276:immunology*; D006255:Rhinitis, Allergic, Seasonal / Q000097:blood / Q000276:immunology*
D018343:Receptors, Adrenergic, beta-2; D000242:Cyclic AMP; D007545:Isoproterenol