Summary

Systemic sclerosis (SSc) is characterized by extensive collagen deposition, microvasculopathy and autoantibodies. All three features can be promoted by activation of T cells and B cells. T cells are of Th2 type producing profibrotic cytokines IL-4 and IL-13 and inducing dendritic cell maturation that promotes Th2 response. B cells are overactivated and promote fibrosis by autoantibodies that activate fibroblasts or inhibit the degradation of extracellular matrix. They also promote fibrosis by cell-cell contact with fibroblasts or dendritic cells. B cells, through autoantibodies, may promote vasoconstriction and obliterative vasculopathy. They may also sustain activation of T cells by functioning as antigen-presenting cells. An immunoregulatory subset of B cells, namely IL-10-producing Bregs, is decreased in SSc. Finally, B cells have a critical role in animal models of SSc. All this evidence suggests an important role for B cells in the pathogenesis of SSc and makes B cells a potential target for therapeutic intervention in this disease.