Role of antigen receptor affinity in T cell-independent antibody responses in vivo.
To examine how B cell receptor affinity affects clonal selection in thymus-independent type 2 (TI-2) immune responses, we produced mice with antibodies that showed a 40-fold difference in affinity for the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP). The difference in the responses of high- and low-affinity B cells to NP-Ficoll was only twofold. However, in competition experiments only the high-affinity B cells responded to antigen. CD19 deficiency increased the affinity threshold of TI-2 responses, whereas Lyn deficiency enhanced clonal expansion but abrogated B cell terminal differentiation. Thus, in TI-2 immune responses, large differences in affinity produce only small differences in the intrinsic ability of B cells to respond to antigen, and selection for high-affinity clones is due to clonal competition during the earliest stages of the response.
Pubmed ID: 11896394 RIS Download
Animals | Antigens, CD | Antigens, CD19 | Antigens, Differentiation, B-Lymphocyte | Apoptosis | B-Lymphocytes | Binding, Competitive | Cell Adhesion Molecules | Cell Division | Gene Targeting | Haptens | Immunoglobulin Heavy Chains | Immunoglobulin Variable Region | Lectins | Mice | Mice, Inbred C57BL | Nitrophenols | Phenylacetates | Receptors, Antigen, B-Cell | Sialic Acid Binding Ig-like Lectin 2 | T-Lymphocytes | src-Family Kinases