Histamine release from human leukocytes: Modulation by cadmium ion

The effect of cadmium on histamine release was studied in relation to the role of calcium. The antigenic histamine release from peripheral leukocytes of ragweed-sensitive patients was inhibited in the presence of cadmium (>10 −5 M). Spontaneous histamine release was not affected by cadmium except for an enhancement observed in high concentrations (≥10 −3 M). Cadmium did not seem to affect the first stage of histamine release but to act mainly on the calcium-dependent second stage. Increasing the level of calcium in the medium could antagonize the inhibitory effect of cadmium. The effect of cadmium could be totally abolished by deuterium oxide and partially by dibutyryl cyclic adenosine monophosphate (AMP) in certain concentrations. These results would indicate that: (1) cadmium acts as an antagonist of calcium and can be used for the study of the role of calcium in histamine release, (2) the action of calcium in the histamine release reaction seems to be related to the microtubular system, (3) cyclic AMP may potentiate histamine release when the action of calcium is inhibited.