Influence of complement C3 amount on IgG responses in early life: immunization with C3b-conjugated antigen increases murine neonatal antibody responses.
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.
Pihlgren
Maria
M
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
Fulurija
Alma
A
Villiers
Marie-Bernadette
MB
Tougne
Chantal
C
Lambert
Paul-Henri
PH
Villiers
Christian L
CL
Siegrist
Claire-Anne
CA
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
D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D013745:Tetanus Toxoid; D003179:Complement C3b; D010047:Ovalbumin