title: Antigen-independent selection of T15 idiotype during B-cell ontogeny in mice.
abstract: Precursors of B cells capable of responding to a T-independent form of phosphorylcholine (PC) in splenic focus assays were detected in the spleens of neonatal mice as early as 4 days after birth. The earliest anti-PC B cells were T15-. T15+ foci-forming B cells were first detected 6 days after birth and expanded rapidly to constitute greater than 80% of the total PC-specific foci by day 10. Injection of heat-killed S. pneumoniae (R36A) into neonatal mice resulted in priming of the antibody response to PC, with an idiotype profile reflecting that of precursors of foci-forming B cells at the time of antigen administration. Priming of 2-day-old mice with 2 x 10(6) and 2 x 10(7) R36A induced a five- and ten-fold increase in the antibody response to phosphorylcholine 6 to 8 weeks later. However, only 10 to 15% of the serum antibodies expressed the normally dominant T15 idiotype. Doses below 2 x 10(5) R36A showed no detectable priming activity. PC-specific hybridomas derived from mice injected with 2 x 10(7) R36A 2 days after birth lacked the idiotypic and molecular characteristics typical of T15+ antibodies. Antibodies to phosphorylcholine, raised by immunization of 6-week-old mice are normally protective against pneumococcal infection. However, serum antibodies from mice treated with R36A 2 days after birth and responding to phosphorylcholine following challenge with R36A at 6 weeks of age failed to protect against deliberate infection with virulent S. pneumoniae. These observations imply that the antigen phosphorylcholine does not play a role in the selective expansion and dominant expression of the T15 idiotype.
authors.affiliation: Department of Microbiology, University of Alabama, Birmingham 35294.
authors.forename: M
authors.initials: M
authors.lastname: Vakil
authors.forename: D E
authors.initials: DE
authors.lastname: Briles
authors.forename: J F
authors.initials: JF
authors.lastname: Kearney
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000276:immunology; D000833:Animals, Suckling / Q000254:growth & development / Q000276:immunology; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000145:classification* / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D000955:Antigens, T-Independent / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation; D002999:Clone Cells / Q000276:immunology; D007114:Immunization; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D051379:Mice / Q000254:growth & development / Q000276:immunology*; D008807:Mice, Inbred BALB C / Q000254:growth & development / Q000276:immunology; D008808:Mice, Inbred CBA / Q000254:growth & development / Q000276:immunology; D008811:Mice, Inbred DBA / Q000254:growth & development / Q000276:immunology; D010767:Phosphorylcholine / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D000955:Antigens, T-Independent; D007130:Immunoglobulin Idiotypes; D010767:Phosphorylcholine