Anergic CD8+ T Lymphocytes Have Impaired NF-κB Activation with Defects in p65 Phosphorylation and Acetylation

Abstract

Because of the cytotoxic potential of CD8+ T cells, maintenance of CD8+ peripheral tolerance is extremely important. A major peripheral tolerance mechanism is the induction of anergy, a refractory state in which proliferation and IL-2 production are inhibited. We used a TCR transgenic mouse model to investigate the signaling defects in CD8+ T cells rendered anergic in vivo. In addition to a previously reported alteration in calcium/NFAT signaling, we also found a defect in NF-κB–mediated gene transcription. This was not due to blockade of early NF-κB activation events, including IκB degradation and NF-κB nuclear translocation, as these occurred normally in tolerant T cells. However, we discovered that anergic cells failed to phosphorylate the NF-κB p65 subunit at Ser311 and also failed to acetylate p65 at Lys310. Both of these modifications have been implicated as critical for NF-κB transactivation capacity, and thus, our results suggest that defects in key phosphorylation and acetylation events are important for the inhibition of NF-κB activity (and subsequent T cell function) in anergic CD8+ T cells.