BASOPHILS AND THE T HELPER 2 ENVIRONMENT CAN PROMOTE THE DEVELOPMENT OF LUPUS NEPHRITIS

In systemic lupus erythematosus (SLE) self-reactive antibodies can target the kidney (lupus nephritis) leading to functional failure and possible mortality. We report that activation of basophils by autoreactive IgE, causes their homing to lymph nodes, promoting T(H)2 cell differentiation, and enhancing the production of self-reactive antibodies that cause lupus-like nephritis in Lyn(−/−) mice. SLE patients also have elevated serum IgE, self-reactive IgE's, and activated basophils that express CD62L and the MHC Class II molecule, HLA-DR; parameters that were found to be associated with increased disease activity and active lupus nephritis. Basophils were also present in the lymph nodes and spleen of SLE patients. Thus, in Lyn(−/−) mice, basophils and IgE autoantibodies amplify autoantibody production that leads to lupus nephritis, and in SLE patients, the presence of IgE autoantibodies and activated basophils are factors associated with disease activity and nephritis.