Reducing the pool of naïve T-cells may help control colitis by removing cells that would become activated or develop into memory cells following exposure to Hb. Regardless of whether anti-IL-7Rα efficacy is due to specifically decreasing IL-7Rαhigh or IL-7Rα+ T cells in general, the combined effect of reducing both naïve and activated/memory T cells was associated with reduced colitis in Mdr1a−/− mice. This evidence concerns the gene GSTM1 and colitis.