Figure 3.

Flow cytometric analyses of cell populations in B16 tumour-bearing mice. C57BL/6 mice with 5–6-mm-diameter tumours were irradiated with 0 or 10 Gy. Cells were harvested from tumour (Fig. 3a) and spleens (Fig. 3b) and, either 2 or 4 days after the radiation treatment, were stained with antibodies to various immunecell subset markers and analyzed by flow cytometry. Mice without tumours are used as a control in Fig. 3b. Data in Fig. 3a,b represent the subpopulation in total tumour cells and in gated splenic lymphocytes respectively. Figure 3(c) shows CD4⁺ CD25⁺ Foxp3+ T-regulatory cells as a fraction of CD4⁺ cells in both tumour lymphocytes and splenic lymphocytes. Results are shown as mean ± 1 standard error of the mean (SEM) of three to five experiments. (*P< 0·05 as compared with the 0 Gy group in Fig. 3a,c and with the control group in Fig. 3b).