title: Complement activation requirements for histamine release from human leukocytes: influence of purified C3ahu and C5ahu on histamine release.
abstract: The activation of human sera for histamine release by zymosan and anti-BSA-BSA complexes at equivalence was dose dependent and associated with a marked fall in CH50, C3 and C5 hemolytic activities. Heat-aggregated IgG, though able to fix greater than 90% of human CH50 activity and produce a lesser fall in C3 and C5 activities than zymosan and BSA-anti-BSA complexes, was unable to induce basophil histamine release. Chemically purified human C3a and C5a each caused histamine release from human basophils; C5a was more potent than C3a. In addition, neither zymosan nor BSA-anti-BSA complexes released histamine when incubated with homozygous C3-deficient serum. The addition of C3a and C5a at suboptimal concentrations produced an additive effect of histamine release.
mesh_terms: D000706:Anaphylatoxins; D000818:Animals; D000936:Antigen-Antibody Complex; D003167:Complement Activation; D003176:Complement C3; D015926:Complement C3a; D003182:Complement C5; D015936:Complement C5a; D004306:Dose-Response Relationship, Immunologic; D006636:Histamine Release; D006801:Humans; D007962:Leukocytes / Q000276:immunology*; D010455:Peptides; D011817:Rabbits; D015054:Zymosan / Q000494:pharmacology
chemical_list: D000706:Anaphylatoxins; D000936:Antigen-Antibody Complex; D003176:Complement C3; D003182:Complement C5; D010455:Peptides; D015926:Complement C3a; D015936:Complement C5a; D015054:Zymosan