Mouse monoclonal antibodies to pneumococcal C-polysaccharide backbone show restricted usage of VH-DH-JH gene segments and share the same kappa chain.
The immunization of BALB/c mice with heat-killed cells of Streptococcus mitis SK598 allowed the rescue of mouse monoclonal antibodies (mAbs) reactive with the pneumococcal cell wall C-polysaccharide backbone. We report for the first time the genetic and molecular characterization of these mAbs, which altogether reflect a typical thymus-independent type 2 immune response. They were isotype-diverse (IgM, IgG1, IgG2b and IgG3). They made use of restricted and scarcely mutated VH-DH-JH combinations, and the same kappa chain, essentially in germ line configuration. Interestingly, this light chain was also found making up part of an anti-phosphorylcholine mAb. These mAbs were not inhibited by phosphorylcholine and related compounds, nor N-acetylneuraminic acid (NANA), nor the Forssman disaccharide; some of them showed limited reactivity with the meningococcal C polysaccharide. Their CDR-H3s do not show any recognizable patterns resembling those found in antibodies to bacterial polysaccharides that have already been characterized.
Area de Inmunología, Facultad de Medicina, Universidad de Oviedo, c/ Julián, Clavería s/n, 33006 Oviedo, Spain.
Alba
A
Fernández-Sánchez
Marcos
M
García-Ocaña
Juan R
JR
de los Toyos
D000818:Animals; D000907:Antibodies, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D005260:Female; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology; D007145:Immunoglobulin kappa-Chains / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D034361:Streptococcus mitis / Q000276:immunology*
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains; D011135:Polysaccharides, Bacterial; C027158:polysaccharide C-substance (Streptococcus)