title: Comparison of complement activity in adult and preterm sheep serum.
abstract: OBJECTIVE
  Functional complement activity is routinely measured utilizing rabbit antibody-sensitized sheep erythrocytes. Due to complement inhibitor expression on erythrocytes, the development of an alternative method to measure complement function in sheep serum was required.
  
  
  METHODS
  Several species of target erythrocyte and sensitizing antibody were investigated for improved measurement of complement function testing.
  
  
  CONCLUSIONS
  Guinea pig erythrocytes were identified as the optimal target, although sensitizing them with rabbit antiguinea pig erythrocyte antibody did not enhance the lysis by maternal sheep serum. In contrast, preterm neonatal sheep serum was unable to efficiently lyse guinea pig erythrocytes unless pre-sensitized with antibody. Further investigation revealed that maternal serum contained high levels of antibodies that cross-reacted with guinea pig and rabbit erythrocytes, while no cross-reacting antierythrocyte antibodies were found in preterm neonatal serum. Therefore, unlike primates, rabbits, and guinea pigs, no transplacental transfer of maternal IgG to foetal sheep occurs. Use of exogenous complement regulators is often used to dissect the contribution of complement to disease pathogenesis; however, we found that while full-length soluble human complement receptor 1 (sCR1, CDX-1135) was able to inhibit lysis of guinea pig erythrocytes by human and rat serum, no inhibition of sheep serum could be observed. Investigation of complement contribution to disease pathogenesis in the future will require the identification of an inhibitor that is effective against sheep complement.
authors.affiliation: School of Medicine, Institute of Molecular and Experimental Medicine, Cardiff University, University Hospital of Wales, Cardiff, UK; Department of Pathology, Nineveh College of Medicine, University of Mosul, Mosul, Iraq.
authors.forename: Shatha
authors.initials: S
authors.lastname: Ahmed
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Kemp
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Payne
authors.forename: Suhas G
authors.initials: SG
authors.lastname: Kallapur
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Stock
authors.forename: Henry C
authors.initials: HC
authors.lastname: Marsh
authors.forename: Alan H
authors.initials: AH
authors.lastname: Jobe
authors.forename: John P
authors.initials: JP
authors.lastname: Newnham
authors.forename: Owen B
authors.initials: OB
authors.lastname: Spiller
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D000910:Antibodies, Heterophile / Q000276:immunology; D002645:Chickens; D003165:Complement System Proteins / Q000032:analysis*; D003429:Cross Reactions; D004912:Erythrocytes; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D005333:Fetus / Q000276:immunology; D006168:Guinea Pigs; D006461:Hemolysis; D006801:Humans; D010446:Peptide Fragments / Q000494:pharmacology; D011247:Pregnancy; D011817:Rabbits; D051381:Rats; D011951:Receptors, Complement / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology; D012756:Sheep / Q000097:blood*; D013045:Species Specificity
chemical_list: D000910:Antibodies, Heterophile; D010446:Peptide Fragments; D011951:Receptors, Complement; D011994:Recombinant Proteins; D003165:Complement System Proteins
keywords: Antibody; complement; functional assay; preterm neonate; sheep