Fig. 2
An early accumulation of immunosuppressive M-MDSC is specifically associated with the peritoneal response to carcinogenic CNT-7 in Wistar rats. a Flow cytometry dot plots show the proportions of leukocyte sub-populations present in peritoneal lavages obtained from CNT-7-treated rats (2 mg) at day 7 and identified by using CD11b/c and His48 markers (a = macrophages, b = M-MDSC, c = neutrophils, d = granulocytes, i.e. eosinophils and mast cells). Microscopic views (Diff-Quick staining, 400x) of FACS-sorted monocytic CD11b/cint and His48hi Myeloid Derived Suppressor Cells (M- MDSC) (b) and CD11b/cint and His48int neutrophils (c) freshly obtained from peritoneal cells of CNT-7-treated rats at day 7. Proportion of (b) M-MDSC and (c) neutrophils in the peritoneal lavages performed on CNT-7- or crocidolite asbestos- (Asb) treated Wistar rats at different time points (from 1 to 30 days) after ip injection of 2 mg particles. Each bar represents mean ± SEM of 4–5 observations. The results were statistically analyzed using the Dunnett’s Multiple Comparison test. ** = p < 0.01, *** = p < 0.001 indicate a statistically significant difference with saline-treated rats (day 0). In vitro anti-proliferative activity of different numbers of M-MDSC (d-f) or neutrophils (e-g) purified at different time points (from 1 to 30 days) from CNT-7- (d-e) or asbestos- (f-g) treated rats (2 mg) on spleen T lymphocytes activated with anti-CD3/CD28 antibodies. Graphs represent the average level of 3H-thymidine incorporation expressed as percent of controls (activated T lymphocytes alone) for each M-MDSC or neutrophils/splenocytes ratio. Each bar represents mean ± SEM. The results were statistically analyzed using the Dunnett’s Multiple Comparison test. * = p < 0.05, $ = p < 0.01, # = p < 0.001 indicate a statistically significant difference with activated splenocytes cultured alone