Abstract
We previously found a murine B cell differentiation antigen, Lp-3, which can detect certain but not all populations of activated B cells. In the present study, we found that the Lp-3 expressions on the B cells responsible for spontaneous IgM and IgG class-anti-DNA antibody synthesis in systemic lupus erythematosus (SLE) -prone NZB×NZW F1 mice are Lp-3- and Lp-3+, respectively, Using SDS-PAGE analysis, Lp-3 was found to be a single polypeptide chain with an intramolecular disulfide bond (s), having a molecular mass of 132kDa. Analysis of the amino acid sequence of peptide fragments showed that the molecule has a structure belonging to the immunoglobulin superfamily. These findings suggest that the Lp-3 is a receptor or receptor-associated molecule for a certain B cell activation or differentiation factor, and is related to the immunoglobulin class switch of anti-DNA antibodies from IgM to IgG, which is an event associated with the development of lupus nephritis.
