Figure 6. Immunohistochemistry for IDO and CD3+ and CD8+ lymphocytes in the corneal endothelium. A-B: IDO; C: CD3+ T – lymphocytes; D: CD8+ T - lymphocytes. Magnification A-D is 400X; inlays in A-D represent twofold enlarged details from respective images marked by arrows. A: non-rejected cornea negative for IDO (A) and no T-cell infiltration (data not shown); B-D: rejected cornea transplant positive for IDO (B) with infiltration of CD3 + T-lymphocytes (C; arrow, arrowhead) and CD8+ T-lymphocytes (D; arrow and arrowhead) within IDO-positive (B) cornea. B-D are images from serial sections.