The complement system.
D000707:Anaphylaxis; D000818:Animals; D000937:Antigen-Antibody Reactions; D002462:Cell Membrane; D003165:Complement System Proteins; D004789:Enzyme Activation; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D007109:Immunity; D051379:Mice; D008854:Microscopy, Electron; D008970:Molecular Weight; D011414:Properdin / Q000378:metabolism; D012756:Sheep
D011414:Properdin; D003165:Complement System Proteins