Figure 1.

Increase in the proportion of regulatory T cells in a murine model for mesothelioma. (a) Left: The transcription factor Foxp3, a hallmark of naturally arising CD4⁺CD25⁺ Tregs, was expressed inside the tumor (red staining). Cells were counterstained with haematoxylin. [Magnification 200×] Right: A higher magnification (400×) shows the appearance of Foxp3⁺ cells as indicated by arrows. (b) Tregs (blue staining) were occasionally present in the near vicinity of CD8⁺ cells (red staining) [Magnification 1000×]. (c) and (d) Percentage of Tregs (defined as CD4⁺CD25⁺Foxp3⁺ cells) from total CD4⁺ T cells in the peripheral blood and draining lymph nodes is significantly higher at day 10 in tumor-bearing mice compared to healthy mice as observed by flow cytometry. (e) A positive correlation was found between the total tumor weight and the percentage of Tregs, measured in the lymph nodes of tumor-bearing mice. Five mice were euthanized at day 10 (tumor weight varied from 0.1 gram to 1 gram) and three mice at stage with ill health (tumor weight 1.5 to 2.1 gram). Correlation coefficient of the trend line (R-squared) is 0.780 (P  value is  .0039).