Enhanced response of autoantibody-secreting B cells from young NZB/NZW mice to T-cell-derived differentiation signals.

Spleen cells from young NZB/NZW mice spontaneously produce IgM antihistone and anti-DNA antibodies in culture, and this in vitro autoantibody production is T-cell dependent. In the present studies, we investigated the response of young autoantibody-producing NZB/NZW B cells to various T-cell-derived signals. Stimulation with unprimed allogeneic T cells resulted in a 10- to 20-fold increase in IgM antihistone and anti-DNA antibody production compared with cultures of B cells alone. The responding cells were found in the large B-cell fraction after separation on Percoll gradients. Allo-stimulated B cells from nonautoimmune mice produced much lower absolute amounts of IgM autoantibodies as well as total IgM compared with NZB/NZW cells. Marked IgM antinuclear antibody and total IgM production was also observed when NZB/NZW B cells were cultured with supernatants from TH2 but not TH1 T-helper clones. Although B cells from nonautoimmune mice produced high levels of autoantibodies after stimulation with lipopolysaccharide, only minimal levels were secreted in response to the active supernatants. These results suggest that young NZB/NZW mice have IgM autoantibody-producing B cells that are more sensitive to certain T-cell-derived signals compared with B cells from normal mice. Although these hyperresponsive NZB/NZW cells appear to be in an advanced stage of activation, they require additional T-cell signals to express this abnormality.