Contribution of Lyb 5+ and Lyb 5- Cells to the Primary and Secondary Phosphocholine-Specific Antibody Response

摘要

Due to a mutation on their X-chromosome, CBA/N mice lack the Lyb-5(+) subset of B cells. The loss of this B cell subset results in a profound alteration in the immune response of these mice to the hapten phosphocholine (PC). Thus, when these mice are immunized with high doses of PC-KLH (200 micrograms) in CFA, they: 1) fail to produce IgM anti-PC antibodies; 2) produce little or no anti-PC antibody bearing the normally predominant T15-idiotype; and 3) produce IgG anti-PC antibodies only late in the primary response. In order to more fully delineate this defect in responsiveness to PC, the splenic focus assay was used to analyze Lyb-5(-) B cell precursors from both normal and immune defective mice. Lyb-5(-) cells were obtained from normal (CBA/N x DBA/2)F sub 1 (CD) female spleens by treatment with anti-Lyb-5(-) serum and complement. These normal Lyb-5(-) cells from immune defective CD male mice were stimulated in vitro with either PC-HY or TNP-Hy in the presence of Hy-primed T helper cells. The results demonstrate that primary Lyb-5(-) PC-specific B cells fail to respond in the splenic focus assay, while secondary Lyb-5(-) PC-specific precursors respond normally, and that both primary and secondary Lyb-5(-) TNP-specific precursors respond in the splenic focus assay. These data suggest that Lyb-5(-) PC-specific precursors must differentiate into memory cells before they can be activated to secrete antibody, and they also indicate that the Lyb-5(-) B cell subset may be composed of two subsets with different activation requirements.