CYCLIC-AMP AGONIST INHIBITION INCREASES AT LOW-LEVELS OF HISTAMINE-RELEASE FROM HUMAN BASOPHILS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 218  (3) , 642-646
Abstract
The relationship between the intensity of the signal for antigen-induced, IgE-mediated, histamine release from human basophils and the concentration of agonist needed to inhibit release was determined. The agonists, prostaglandin[PG]E1, dimaprit, fenoterol, isobutylmethylxanthine and dibutyryl cAMP, all act by increasing the cAMP level. Each agonist was 10- to 1000-fold more potent (relative ID50 [median inhibitory dose]) at low levels of histamine release (5-10% of total histamine) than at high levels (50-80%). The inhibitory potential of a drug is a function of the concentration of antigen used to initiate the response. The results are more in accord with the inhibitory profile of the drugs in human lung tissue. In vivo release is likely to be low and this may be the level at which to evaluate drugs in vitro.

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