Background-Oral immunotherapy (OIT) has been thought to induce clinical desensitization to allergenic foods, but trials coupling the clinical response and immunologic effects of peanut OIT have not been reported.

Much is known about how T cell receptor (TCR) engagement leads to T cell activation; however, the mechanisms terminating TCR signaling remain less clear. Diacylglycerol, generated after TCR ligation, is essential in T cells. Its function must be controlled tightly to maintain normal T cell homeostasis. Previous studies have shown that diacylglycerol kinase zeta (DGKzeta), which converts diacylglycerol to phosphatidic acid, can inhibit TCR signaling. Here we show that DGKzeta-deficient T cells are hyperresponsive to TCR stimulation both ex vivo and in vivo. Furthermore, DGKzeta-deficient mice mounted a more robust immune response to lymphocytic choriomeningitis virus infection than did wild-type mice. These results demonstrate the importance of DGKzeta as a physiological negative regulator of TCR signaling and T cell activation.

Summary The mammalian target of rapamycin (mTOR) is a key regulator of cell growth and metabolism. It associates with multiple proteins and forms two distinct signaling complexes, mTORC1 and mTORC2. Accumulating evidence has revealed critical roles for intact mTOR signaling during T cell activation and responses to microbial infection. However, the importance of mTOR regulation in T cells has yet to be explored. The TSC1/TSC2 complex has been shown to inhibit mTORC1 signaling in cell line models. We show here that deletion of TSC1 in the murine T cell lineage resulted in a dramatic reduction of the peripheral T cell pool, correlating with increased cell death. While mTORC1 is constitutively activated, mTORC2 signaling, reflected by Akt phosphorylation and activity, is decreased in TSC1-deficient T cells. Furthermore, TSC1-deficient T cells contain elevated reactive oxygen species and exhibit decreased mitochondrial content and membrane potential, which is correlated with the activation of the intrinsic death pathway. Together, our results demonstrate that TSC1 differentially regulates mTORC1 and mTORC2 activity, promotes T cell survival, and is critical for normal mitochondrial homeostasis in T cells.