Avidity maturation, repertoire shift, and strain differences in antibodies to bacterial levan, a type 2 thymus-independent polysaccharide antigen.
Our previous studies of 102 mAb from mice injected with bacterial levan (BL), a beta(2-->6) linked polyfructosan with beta(2-->1) branch points (inulin determinant, In) showed that BALB/c and CBA/Ca mAb differed in VH and VL gene family usage and fine specificity. We now show that BALB/c and CBA/Ca mAb used different VHJ606 germ-line genes in response to BL: V14A in BALB/c and a previously unidentified gene in CBA/Ca. CBA/Ca mice were found to lack the BALB/c V14A gene. Also, we have compared the responses to one (primary, 1 degree) or two (secondary, 2 degrees) injections of polysaccharide. The secondary BALB/c anti-BL panel has been expanded to a total of 22 mAb, and we report here the isotype, fine specificity, and VH/VL usage of the new mAb. Eight of nine primary BALB/c In-binding mAb were germ-line, whereas both secondary BALB/c In-binding mAb that were sequenced differed from the BALB/c germ-line gene V14A. Germ-line primary mAb were low avidity whereas all five secondary mAb and the one non-germ-line primary were high avidity. There was also a repertoire shift from approximately 90% VHJ606/V kappa 11 in primary mAb to only 50% in secondary mAb (p = 0.002). The data presented provide evidence that avidity maturation and repertoire shifts, features usually associated with a memory response to thymus-dependent Ags, also can occur in response to a second immunization with a thymus-independent type 2 polysaccharide Ag.
Boswell
C M
CM
Office of Therapeutic Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Stein
K E
KE
D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000235:genetics*; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000235:genetics; D000915:Antibody Affinity / Q000235:genetics*; D000955:Antigens, T-Independent / Q000276:immunology*; D001483:Base Sequence; D005260:Female; D005630:Fructans / Q000276:immunology*; D005803:Genes, Immunoglobulin / Q000276:immunology; D017578:Immunoglobulin Class Switching / Q000276:immunology*; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007444:Inulin / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013045:Species Specificity
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000955:Antigens, T-Independent; D005630:Fructans; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D011135:Polysaccharides, Bacterial; D007444:Inulin; C072599:levan