In the present study, the differential analysis of naive, effector memory and central memory T cells also revealed that IL-22 has no general influence on the development of memory and central memory T cells after infection with Mtb. Reduced numbers of naive CD4+ T cells at early stages of infection day may be explained by slightly reduced expression of the IL-22-dependent chemokines MMP-1 and CXCL-10 in IL-22−/− mice, which are involved in activation and recruitment of T cells [56], [57], [70], [71] (data not shown). The gene discussed is MMP1; the disease is infection.