Rate of Helios+ T regulatory lymphocyte subpopulations in representative tissues. Percentages refer to CD4+ Foxp3+ He+ life lymphocytes (Q2) among CD4+ Foxp3+ life lymphocytes (Q1 + Q2). MLN, mesenteric lymph node; SPN, spleen; H2O, water-fed control group; MTX, methotrexate treated mice; MMF, mofetil mycophenolate treated and immunized (experimental autoimmune uveitis) mice. Time-point = 2 weeks post-immunization.