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Altered selection processes of B lymphocytes in autoimmune NZB/W mice, despite intact central tolerance against DNA

Anti‐DNA autoantibodies are the hallmark of systemic lupus erythematosus and the (NZB×NZW)F1 (NZB/W) murine model. To investigate potential defects in B cell tolerance, we followed the development of anti‐DNA‐specific B cells in 2–5‐month‐old mice transgenic for an unmutated μH chain in the normal C57BL/6 and in the NZB/W background. When the transgenic H chain was combined witha random κ L chain repertoire about 60% of the antibodies bound to DNA. The analysis of the B cell repertoire in the spleen showed extensive receptor editing and a deletion of DNA reactivity in the C57BL/6 as well as in the autoimmune NZB/W background. NZB/W compared to C57BL/6 transgenic mice had a higher frequency of anti‐DNA B cells among follicular B cells that were not censored by central tolerance mechanisms. Furthermore, positive selection of B cells with a recurrent rearrangement into the marginal zone compartment was more pronounced in NZB/W mice. Serum levels of transgenic IgM and of anti‐DNA autoantibodies indicate a polyclonal activation of hyperactive B cells in the transgenic NZB/W mice. We propose different B cell receptor signaling thresholds for the NZB/W compared to C57BL/6 B cells. This could explain the quantitative differences in the B cell repertoire as well as the hyperactivity of B cells from NZB/W mice.