CD4 and colitis: However, colitis can also be induced in mice by exposure to Helicobacter hepaticus or Citrobacter rodentium, by treatment with anti-CD40 monoclonal antibodies (mAbs), by transfer of CD4+ T cells depleted of regulatory T cells into immune deficient mice, or by chemical damage to the colon epithelium, for example, by treatment with dextran sodium sulfate (DSS).