Endocrine Abstracts

In vitro expanded antigen specific CD4+CD25+ regulatory T cells (Tregs), have been shown to suppress autoimmune diabetes, suggesting a novel approach to cellular immunotherapy for autoimmunity. However to interfere with ongoing disease requires at least 10⁶ in vitro expanded antigen specific Tregs which are difficult to obtain from a polyclonal repertoire. Hence an alternative approach would be to instruct naïve or antigen specific CD4+T cells to obtain regulatory function. Indeed retroviral transduction of antigen specific T cells withFoxp3, a Treg lineage specific transcription factor, results in the generation of Tregs that can interfere with established autoimmunity in a non-lymphopenic nonobese diabetic (NOD) mouse model. However, conditions for transduction into NOD T cells have not yet been optimized. Furthermore very little is known about the in vivo effect of these Foxp3 transduced antigen specific T cells. Here we show that ecotropic pseudotyped viruses are more efficient at transducing NOD CD4+T cells than VSVG pseudotyped viruses. In addition retroviral transduction of Foxp3 into NOD CD4+ primary T cells carrying the transgenic TCR from an islet Ag-specific T cell clone, BDC2.5, confers a Treg phenotype on these cells as they exhibit Treg signature characteristics such as in vitro anergy, suppressive capacity and upregulation of CD62L, CD25 and GITR. Adoptive transfer of Foxp3 transduced BDC T cells into NOD recipients shows that the cells home and proliferate in an antigen specific manner.