title: Complement-like activity in the sea star, Asterias forbesi.
abstract: The coelomic fluid (CF) of Asterias forbesi was examined for the presence of complement-like activity. Cell-free CF contains hemolytic activity for unsensitized rabbit erythrocytes (E) but not unsensitized or antibody-coated sheep E. Target E sensitivity is not dependent upon phylogenetic proximity of erythrocyte species to Asterias. The activity is optimally assayed at 25 degrees C, has a sigmoidal dose-response curve, and is heat-sensitive (56 degrees C). The activity is divalent cation dependent, although Ca++ and Mg++ are not required. Nonlytic CF does not contain an inhibitor; rather, combining nonlytic and lytic CFs results in an increase in hemolysis. Activity can be consumed by treatment with zymosan, pronase, trypsin, and PMSF. Enzymatic desialidation converts sheep E into activators of the hemolytic pathway. No phospholipase activity is present in CF. Biological function is demonstrated by bactericidal activity against Vibrio tubiashii by lytic CF. These results suggest that a primitive complement system is operating in Asterias.
authors.affiliation: Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205.
authors.forename: L A
authors.initials: LA
authors.lastname: Leonard
authors.forename: J D
authors.initials: JD
authors.lastname: Strandberg
authors.forename: J A
authors.initials: JA
authors.lastname: Winkelstein
mesh_terms: D000818:Animals; D001419:Bacteria; D001826:Body Fluids / Q000032:analysis; D002413:Cations, Divalent / Q000494:pharmacology; D003165:Complement System Proteins; D006460:Hemolysin Proteins / Q000302:isolation & purification; D006461:Hemolysis; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D011506:Proteins / Q000302:isolation & purification; D011817:Rabbits; D012794:Sialic Acids / Q000032:analysis; D013215:Starfish / Q000276:immunology*; D015054:Zymosan / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D006460:Hemolysin Proteins; D011506:Proteins; D012794:Sialic Acids; D010664:Phenylmethylsulfonyl Fluoride; D003165:Complement System Proteins; D015054:Zymosan