CD4 and systemic lupus erythematosus: Furthermore it is unlikely that IL-10 itself, which can induce apoptosis in several cell types like mast cells, macrophages and CD4+ T cells from SLE patients [36], [37] is responsible for the preferential apoptosis of IL-10 producing Tregs since in vivo CD28SA activated IL-10 producing and non-producing Tregs express comparable and low levels of IL-10R (Fig. S3B).