In vivo cell transfer assay to detect autoreactive T cell subsets

Among the methods used in molecular biology, in vitro biochemical assays are more common, whereas in vivo assays, including the use of animal models, are less widely employed. In our studies on systemic lupus erythematosus (SLE), we have identified a novel T cell subtype termed "autoantibody-inducing CD4 T cells" (aiCD4 T cell) that is responsible for the development of autoimmunity. In order to identify and isolate these cells, we developed a new technique that involves the transfer of candidate T cell subpopulations into naïve mice and assaying for the development of autoantibodies in the recipient mice. We have previously described an experimental system in which mice not normally prone to autoimmune diseases can be induced to develop experimental SLE. In this experimental system, autoantibody-inducing CD4 T (aiCD4 T) cells are generated via de novo T cell receptor revision at peripheral lymphoid organs. These aiCD4 T cells not only induce a variety of autoantibodies but also promote the final differentiation of CD8 T cells into cytotoxic T lymphocytes, resulting in a pathology identical to SLE. We needed to develop a new methodology to isolate this subpopulation of aiCD4 T cells. Here we describe an in vivo assay to detect and isolate aiCD4 T cells by transferring the candidate cells into naïve recipient mice and monitoring the production of the appropriate antibody or cytokine.