title: Haemolysis of human erythrocytes heavily sensitized with sheep amboceptor by sheep complement chelated with EGTA or Mg2+-EGTA.
abstract: Human erythrocytes sensitized with an agglutinating dose of either sheep anti-human erythrocyte antiserum, IgM, slow or fast gamma-globulin antibody are haemolysed by foetal lamb or sheep serum complement (C) in the presence of ethyleneglycoltetraacetic acid (EGTA) or Mg2+-EGTA but not ethylenediaminetetraacetic acid (EDTA) or triethylenetetraminehexaacetic acid (TTHA). Dialysis of the C source against phosphate buffered saline rendered it inactive, but addition of Mg2+ or Mg2+-EGTA restored haemolytic activity. Haemolysis of sensitized erythrocytes took place more rapidly in buffer containing Ca2+ and Mg2+ than in EGTA or Mg2+-EGTA. Heating the C source at 50 degrees C for 30 min or 56 degree C for 3 min abolished haemolytic activity. In the presence of EGTA or Mg2+-EGTA, haemolytic activity was restored to 50 degrees C-heated serum by a CM-cellulose fraction that contained sheep factor B. These results show that sheep C, in the presence of EGTA or Mg2+-EGTA will haemolyse human erythrocytes heavily sensitized with sheep amboceptor. The alternative pathway of sheep C is thought to be involved.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D003167:Complement Activation / Q000187:drug effects*; D004533:Egtazic Acid / Q000494:pharmacology*; D004912:Erythrocytes / Q000276:immunology; D005026:Ethylene Glycols / Q000494:pharmacology*; D006461:Hemolysis; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D008274:Magnesium / Q000494:pharmacology; D012756:Sheep / Q000276:immunology*; D005719:gamma-Globulins / Q000276:immunology
chemical_list: D000888:Antibodies, Anti-Idiotypic; D005026:Ethylene Glycols; D007075:Immunoglobulin M; D005719:gamma-Globulins; D004533:Egtazic Acid; D008274:Magnesium