NEW ROLE FOR B-CELLS IN SYSTEMIC AUTOIMMUNITY - B-CELLS PROMOTE SPONTANEOUS T-CELL ACTIVATION IN MRL-IPR IPR MICE/

A conventional view of the pathogenesis of systemic lupus erythematosu s has emerged, The role of B cells is to secrete pathogenic autoantibo dies, while the role of T cells is to provide help for autoantibody-pr oducing B cells. A problem with this view is that spontaneous T cell a ctivation as well as T cell infiltration of organs such as kidney and skin are prominent features in systemic lupus erythematosus patients a nd murine models of lupus, The identification of T cell infiltrates, i n particular, suggests that autoantibody-mediated damage may be only p art of the story and that T cells could also play a primary role in im mune mediated pathology, To test the role of B cells directly, we prev iously generated autoimmune-prone MRL-lpr/lpr mice that lack B cells, The complete absence of T cell infiltrates in these mice was surprisin g, and it prompted us to examine whether a key role of B cells in dise ase evolution is to prime autoreactive T cells, Here we demonstrate, b y comparing B cell-deficient and control mice, that the expansion of a ctivated and memory T cells in the MRL-lpr/lpr mouse is indeed highly dependent on B cells. These results suggest a novel role for 13 cells in autoimmune disregulation.