This phenomenon results in T cells anergy. T lymphocytes can instead undergo clonal arrest, clonal anergy, and clonal editing. Reactive oxygen species are also implicated in activation, anergy and apoptosis of T cells. Therefore, anergy testing is advised in cases where there is suspicion that anergy is present. ILCs, on the contrary, may set the helper T lymphocytes in the state of anergy. T-regulatory cells produce CTLA-4, which can dampen an immune response and lead to increased anergy. Both clonal anergy and clonal deletion have been shown to operate in vetoed T cells. The mechanism of clonal anergy is important to maintain tolerance to many autologous antigens. Rant invented the terms exergy and anergy. However, routine anergy skin testing is not recommended. Deletion or anergy of activated T-cells follows infection. The destroyed exergy has been called anergy. For an isothermal process, exergy and energy are interchangeable terms, and there is no anergy. In fact, lack of further stimulatory signals sends the T cell into anergy. Anergy may be taken advantage of for therapeutic uses.