Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown cause characterized by expansion of autoreactive lymphocytes. Regulatory T cells (Tregs) are a component of the normal immune system and contribute to the maintenance of peripheral tolerance. Treg abnormalities have been associated with several autoimmune diseases and there is interest in the role of Tregs in SLE. We previously demonstrated that transfer of expanded CD4+CD25+CD62LHI Tregs slows the development of lupus in (NZBxNZW)F1 (B/W) mice. However in the absence of Treg specific surface antigens, cell purification remains a compromise between the breadth and purity of the population isolated. Importantly, purified populations always contain Foxp3- effector T cells (Teffs) that theoretically could exacerbate autoimmunity in the recipient. Here we explore the impact of transferring the more comprehensive, but less pure Treg subset defined by CD4+CD25+ expression on development of murine lupus. All cells were FACS sorted and expanded prior to adoptive transfer. Development of proteinuria and survival were measured. We found that exogenous expansion of CD4+CD25+ cells produced a population containing 70-85% CD4+Foxp3+Tregs. Expanded Tregs had higher CTLA-4 and Foxp3 expression, increased in vitro suppression capacity, and prolonged in vivo survival as compared to freshly isolated cells. Adoptive transfer of expanded CD4+CD25+ Tregs inhibited the onset of glomerulonephritis and prolonged survival in mice. Importantly the population of Teff contained within the adoptively transferred cells had reduced survival and proliferation capacity as compared to either co-transferred Tregs or transferred Teffs expanded in the absence of Tregs. These studies demonstrate that adoptive transfer of expanded CD4+CD25+Foxp3+Tregs has the capacity to inhibit the onset of murine lupus and that this capacity is significant despite transfer of co-cultured Teff cells. These data indicate that when co-expanded with regulatory T cells, exogenously activated Teffs from autoimmune patients may not pose a significant risk of promoting disease.
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