Fig. 4. Colitis induced by pathogenic Ptpn22^-/- effector T cells can be controlled by Ptpn22^-/-, but not WT, Tregs.

(A and B) Groups of Rag1^-/- recipients (n = 4 or 5 mice) were injected i.v. with either WT or Ptpn22^-/- naïve CD4⁺CD25^-CDRB^hi cells (4 x 10⁵) alone or together with WT or Ptpn22^-/- CD4⁺CD25⁺ Tregs (5 x 10⁴) obtained from (A) peripheral lymph nodes or (B) thymus in a ratio of 8:1. Mice were assessed for weight loss for up to 70 days after injection, and percentage weight loss is shown. Survival of protected WT/WT and Ptpn22^-/-/Ptpn22^-/- groups was significantly different from that of all other groups; *P < 0.05. (C) To confirm that similar pathology was induced by WT and Ptpn22^-/- colitic T cells, lower intestine sections taken from experimental mice underwent histological analysis. Microphotographs of sections of lower intestine from a representative control C57/BL6 (no injected cells) mouse, a Rag1^-/- recipient injected with WT CD4⁺CD25^-CDRB^hi T cells, and a Rag1^-/- recipient injected with Ptpn22^-/- CD4⁺CD25^-CDRB^hi T cells are shown.