New research findings show in detail how self-reactive T cells — white blood cells dubbed Teffs that mistakenly attack healthy instead of infected cells, thereby causing an autoimmune or an inflammatory response — are held in check by regulatory T cells, or Tregs. Tregs quickly deploy molecular measures to control rapid proliferation of Teffs, to make sure inflammation is kept in check during an immune response. Tregs biochemically interfere with the protein manufacturing machinery in Teff cells. This hinders their abundant production of proteins, which occurs just before cell division, the researchers found. This rapid Treg intervention reduces the size and number of Teff cells to appropriately manage the magnitude of the immune response.