Release of histamine from human basophils was induced by activation of complement using zymosan. The histamine releasing factor resembled C5a on the basis of m.w. (15,000) as well as previous studies showing inactivation by anti C5. Complement induced release of histamine was compared with allergic release of histamine which is mediated through appropriate allergens and reaginic IgE. Previously we demonstrated that the former reaction occurred more quickly. Both reactions were inhibited by drugs which increase intracellular concentrations of cAMP (theophylline, prostaglandin E1, and histamine) or which mimic the action of cAMP (its dibutyryl derivative). Calcium was required for complement mediated release of histamine and an increasing response was observed up to physiologic concentrations (2 mM). Magnesium (0 to 1 mM) did not affect the amount of histamine released. Also, glycolysis was probably required for optimal release by complement, since both 2 deoxyglucose and iodoacetamide were inhibitory. When basophils were partly enriched by depletion of neutrophils and eosinophils, the percentage of histamine released by complement was unchanged. Finally, it was shown that activated complement desensitized basophils from responding to a second challenge by the same stimulus. Cross desensitization was not observed between complement and pollen allergens.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Immunology|
|State||Published - 1976|
ASJC Scopus subject areas
- Immunology and Allergy