Histamine release from human leukocytes: relationships between cyclic nucleotide, calcium, and antigen concentrations

The antigen-induced IgE-mediated release of histamine from human basophils has previously been shown to require calcium, to be inhibited by agents which raise cyclic AMP levels and by high antigen levels, and to be unaffected by cyclic GMP. The interrelationship between these phenomena has been studied. The major findings are: 1) in the region of antigen-excess inhibition dibutyryl cyclic AMP potentiates release; 2) antigen-excess inhibition is seen at lower antigen concentrations when the calcium concentration is reduced from 0.6 to 0.1 mM; and 3) cyclic GMP modestly potentiates release when the calcium concentration is 0.1 mM.