Figure 1.

Schistosoma japonicum infection increased serum interleukin‐10 (IL‐10) levels and T regulatory (Treg) cell frequency but decreased immunosuppressive activity of Treg cells in mice. (a) Eight weeks after infection, serum IL‐10 of S. japonicum‐infected mice was measured by ELISA (n = 4 per group). (b, c) Eight weeks after infection, splenocytes from infected or normal control mice (n = 6 per group) were isolated and stained with PerCP‐Cy5.5 anti‐CD3, FITC anti‐CD4, APC anti‐CD25, PE anti‐Foxp3. Flow cytometry dot plots of CD25⁺ Foxp3⁺ Treg cells gated on CD3⁺ CD4⁺ T cells are shown. Scatter plot shows the average percentages of CD4⁺ CD25⁺ Foxp3⁺ Treg cells in CD4⁺ T cells. (d, e) Histogram profiles of Foxp3 gated on CD3⁺ CD4⁺ CD25⁺ T cells are shown. Scatter plot shows respectively the average MFI of Foxp3 expression in CD3⁺ CD4⁺ CD25⁺ T cells (n = 6 per group). (f) CD4⁺ CD25⁻ T cells (1 × 10⁵/well) from normal control mice were cultured in triplicate wells with normal mouse‐derived antigen‐presenting cells (1 × 10⁵/well), 2 μg/ml of soluble anti‐CD3 and CD4⁺ CD25⁺ T cells (1 × 10⁵/well) purified from either S. japonicum‐infected or normal control mice at 37° for 72 hr (n = 4 per group). Proliferation was determined by ³H‐thymidine incorporation. (g and h) CD4⁺ CD25⁻ T cells from EGFP‐Tg mice and CD4⁺ CD25⁺ Treg cells from either S. japonicum‐infected or normal control mice were co‐cultured as described in (f). The suppressive activity of Treg cells on CD4⁺ CD25⁻ T cells was measured by analysing the expression of Ki‐67 in EGFP ⁺ cells (CD4⁺ CD25⁻ T cells) (n = 5 per group). Histogram profiles of Ki‐67 gated on EGFP ⁺ cells are shown. Scatter plot shows the average percentages of Ki‐67⁺ cells in EGFP ⁺ cells. Each assay has been performed three times on independent cell samples. FCM dot plots or histograms are representative of three independent experiments. Data (means ± SD) are representative of three independent experiments. *P < 0·05, **P < 0·01, ***P < 0·001, n.s., not significant. [Colour figure can be viewed at wileyonlinelibrary.com]