Anti-IgE- and complement-induced histamine release from peripheral leukocytes in normals and atopics.

Anti-IgE- and complement-induced histamine release from isolated basophils was compared in normal and atopic subjects. Activated complement was generated by incubation of a serum pool from normal donors with zymosan. Histamine was measured by a single-isotope radioenzymatic assay. In atopics, the mean histamine release induced by heterologous complement was significantly higher than in normals (p less than or equal to 0.01). Anti-IgE-mediated histamine release showed no differences between atopics and normals. Regarding the histamine release as a function of the age of the donor, we observed significantly higher complement-induced release values in normal children aged 1-10 years compared to those aged 10-20 and greater than 20 years (p less than or equal to 0.05). Anti-IgE-induced histamine release showed no age-related differences in normals or atopic patients. As a high complement-mediated leukocytic histamine release was more commonly found in atopics with heterologous complement, this phenomenon appears not to be due to a higher rate of complement activation in the serum of atopics, but rather to an intrinsic cell abnormality. Moreover, these results suggest that age-related releasability patterns might be considered when studying complement-induced histamine release. Differences between IgE- and complement-mediated histamine release indicated that parameters of releasability must be defined with respect to each stimulus.