title: Conglutination and haemolysis of unsensitized human erythrocytes by bovine serum complement.
abstract: Unsensitized human erythrocytes (E) were haemolyzed by bovine serum to a titre of 1:16-1:32. In the single dilution beyond the haemolytic endpoint, the cells were conglutinated. In dilutions in which haemolysis occurred, cells were conglutinated before being lyzed. With no or minimal haemolysis, conglutination to 1:32-1:64 occurred in tests using insulin-absorbed serum, serum heated at 50 degrees C for 30 min and in tests incubated at 4 degrees C for 30 min. In two-stage tests, EDTA and Mg2+-EGTA prevented bovine C sensitization of human E for conglutination by bovine serum heated at 56 degrees C for 30 min. EDTA prevented haemolysis, but haemolysis to 1:16-1:32 occurred with serum dilutions containing Mg2+-EGTA. Haemolytic activity was restored to serum heated at 50 degrees C by a factor B-containing fraction. Conglutination and haemolysis were blocked by heating serum at 56 degrees C for 30 min and were reduced to low titres by absorbing serum with zymosan. These results strongly suggest that the conglutination reaction involved the classical activation pathway whereas the haemolytic reaction involved the alternative activation pathway. Thus, with dilutions of untreated or treated bovine serum, two C-dependent reactions and the pathways involved can be demonstrated by using unsensitized human E as an indicator system.
mesh_terms: D000371:Agglutination; D000818:Animals; D002417:Cattle; D003170:Complement Pathway, Alternative; D003171:Complement Pathway, Classical; D003165:Complement System Proteins / Q000502:physiology*; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004912:Erythrocytes / Q000502:physiology*; D006461:Hemolysis; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D013696:Temperature
chemical_list: D004533:Egtazic Acid; D003165:Complement System Proteins; D004492:Edetic Acid; D008274:Magnesium