Peripheral immune tolerance

Immune System must be regulated because it can mistakenly attack one's own organs. T cells undergo a primary test called peripheral immune tolerance in a training ground called the thymus, where defective cells that recognize our own body are eliminated. In other words, if the thymus is removed, the immune system goes into overdrive and attacks its own cells. And the gene mutation that causes these runaway T cells is Foxp3. And the T cells that apply the brakes are Tregs.