Canine CD4⁺CD8α⁺ double-positive (dp) T cells of secondary lymphatic and non-lymphatic organs constitutively express CD25 in contrast to CD4⁺CD8α⁺ dp thymocytes.

(A) The expression of CD25 on CD4+ single-positive (sp), CD8α+ sp and CD4+CD8α+ dp T cells was analyzed by flow cytometry. Shown are representative data of Peyer’s patches in comparison to thymus. The numbers in the pseudocolor plots indicate percentages. Two independent experiments have been performed including organs of 4–10 dogs in total. (B + C) Pooled data of CD25 expression on CD4+ sp (green hexagons), CD8α+ sp (blue diamonds), and CD4+CD8α+ dp (red triangles) T cells in indicated organs are depicted. (B) The graphs include normally distributed data values, each symbol represents one individual dog. The horizontal bars indicate mean values. Statistical analysis was performed by One-way ANOVA with Bonferroni’s Multiple Comparison Test (** p < 0.01, *** p < 0.001). (C) The graphs show non-normally distributed data values, each symbol represents one individual dog. The horizontal bars indicate median values. Statistical analysis was performed by One-way ANOVA with Dunn’s Multiple Comparison Test (* p < 0.05, *** p < 0.001).