title: The first component of complement in serum: evidence for a hitherto unrecognized factor in C1 necessary for internal activation.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D003165:Complement System Proteins / Q000378:metabolism*; D004912:Erythrocytes / Q000276:immunology; D006168:Guinea Pigs; D006801:Humans; D012756:Sheep / Q000276:immunology
chemical_list: D000936:Antigen-Antibody Complex; D003165:Complement System Proteins