title: Influence of complement C3 amount on IgG responses in early life: immunization with C3b-conjugated antigen increases murine neonatal antibody responses.
abstract: Complement component C3, which plays an important role in both the innate and adaptative immune response, is present at low level in human infants. We show here that: (i) serum C3 amount is weak also in infant mice, (ii) these young animals fail to upregulate C3 to adult levels following tetanus toxoid immunization, (iii) neonatal macrophages have a limited capacity to synthesize C3 upon LPS exposure, (iv) conjugation of antigen to C3b significantly enhances antibody response elicited in 1-week-old mice--although it does not increase primary IgG response in adult mice. Altogether, this identifies C3 as one of the factors limiting early life antibody response and emphasizes the potential interest of immunization strategies overcoming this limitation.
authors.affiliation: World Health Organization Collaborating Center for Vaccinology and Neonatal Immunology, University of Geneva, CMU, Rue Michel Servet 1, 1211 Geneva 4, Switzerland. maria.pihlgren@medecine.unige.ch
authors.forename: Maria
authors.initials: M
authors.lastname: Pihlgren
authors.forename: Alma
authors.initials: A
authors.lastname: Fulurija
authors.forename: Marie-Bernadette
authors.initials: MB
authors.lastname: Villiers
authors.forename: Chantal
authors.initials: C
authors.lastname: Tougne
authors.forename: Paul-Henri
authors.initials: PH
authors.lastname: Lambert
authors.forename: Christian L
authors.initials: CL
authors.lastname: Villiers
authors.forename: Claire-Anne
authors.initials: CA
authors.lastname: Siegrist
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D003179:Complement C3b / Q000096:biosynthesis / Q000276:immunology*; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D007074:Immunoglobulin G / Q000097:blood*; D008070:Lipopolysaccharides / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology*; D013045:Species Specificity; D013745:Tetanus Toxoid / Q000276:immunology; D015854:Up-Regulation
chemical_list: D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D013745:Tetanus Toxoid; D003179:Complement C3b; D010047:Ovalbumin