Spontaneous histamine release and histamine content in normal subjects and subjects with asthma

Spontaneous histamine release (SHR) from basophils by simple incubation at 37 °C for 60 minutes and histamine content of basophils were assessed in normal subjects, patients with asthma, and methacholine-sensitive subjects without asthma (NAMS). SHR from basophils of normal subjects did not exceed 10% of the total histamine. A significantly higher SHR was observed in basophils from subjects with asthma than from normal subjects (p <0.002). Basophil SHR in patients with asthma not receiving medication was significantly greater than that in patients with asthma receiving medication (p <0.05). SHR from basophils in NAMS subjects was similar to that in normal subjects. SHR was highly dependent on temperature and Ca⁺⁺ and Mg⁺⁺ ions and appeared to be a slower event than anaphylactic release. The mean histamine content per basophil from normal subjects was 1.48 ± 0.13 pg (mean ± SEM). Basophils from subjects with asthma contained significantly less histamine than basophils from normal subjects (p <0.002). Histamine content per basophil from NAMS subjects was slightly lower than histamine content per normal basophil. No apparent relationship was found between the magnitude of SHR and the histamine content per basophil in the patients with asthma not receiving medication. Hypersensitivity to food or exercise does not appear to be essential for high SHR. High SHR appears to bear little, if any, relationship to cell damage or cell death. High SHR may be a factor that could serve as a marker for bronchial asthma. Further studies are needed to define the clinical relationship and pathophysiologic mechanism of SHR.