Impaired IL-4 production by CD8+ T cells in NOD mice is related to a defect of c-Maf binding to the IL-4 promoter. 
CD8(+) T cells play an important role in the induction of the autoimmune response in non-obese diabetic (NOD) mice.  Here we describe abnormalities in the control of cytokine production by NOD CD8(+) T cells.  NOD CD8(+) T cells had an increased propensity to produce IFN-gamma upon TCR activation, in both adult and 2-week-old mice.  NOD CD8(+) T cells had a reduced capacity to produce IL-4 in type 2 conditions compared to CD8(+) T cells from the diabetes-resistant strains BALB/c and C57BL/6.  Both GATA-3 and c-Maf, two positive transactivators for IL-4 gene expression, were expressed in type 2 conditions at comparable levels in NOD CD8(+) T cells.  The GATA-3 was functional since normal levels of IL-5 were produced and the IL-4 promoter was hyperacetylated in NOD CD8(+) T cells.  In contrast, c-Maf failed to bind to its responsive element as determined by chromatin immunoprecipitation (ChIP) assay.  These results suggest that NOD CD8(+) T cells possess an increased propensity to produce IFN-gamma and impaired c-Maf-dependent DNA binding activities in vivo that lead to reduced IL-4 production following TCR activation.  These defects may facilitate the development of the autoimmune response by inducing an overall type 1-biased immune response in NOD mice.