Deuterium-oxide-induced histamine release from basophils of allergic subjects. I. Responsiveness to deuterium oxide requires an activation step.

Basophils from many atopic persons, and especially asthmatic patients, have been shown to release histamine in response to 44% deuterium oxide (D2O), whereas basophils from nonatopic persons do not release histamine. The present experiments analyzed the mechanisms by which D2O mediated release. It was found that although D2O induced release from washed leukocytes, it failed to induce release from whole blood or from leukocytes that had sedimented but had not been washed. The kinetics of release after washing were rapid and were equivalent regardless of the temperature at which cells were sedimented (O degrees or 37 degrees C). Washed cells became desensitized to the action of D2O within 30 to 60 min at 37 degrees C, whereas unwashed leukocytes did not become desensitized. Serum or plasma inhibited D2O-induced release, although high concentrations (1/5) were less inhibitory than lower ones (1/10 to 1/100). Basophils from D2O responders also released histamine in response to a "platelet enhancing factor" (PEF), whereas those from D2O nonresponders did not. As with D2O-mediated release, PEF-mediated release occurred only with washed leukocytes, desensitized within 30 to 60 min at 37 degrees C, and was inhibited by serum. These results suggest that D2O induces histamine release by augmenting the effects of an endogenous activation mechanism, and that PEF acts on the same (D2O-responsive) donors to augment this activation mechanism. Cell activation, as well as desensitization of this activation mechanism, occurs rapidly when basophils are washed free of plasma inhibitors and placed at 37 degrees C.