Reduction of MDSC in tumour-bearing mice after celecoxib-treatment. A) Accumulation of MDSC (characterized by the expression of Gr-1 and CD11b) in tumour-bearing mice receiving control diet or celecoxib diet: day 0 n = 4/4, day 10 n = 5/5, day 15 n = 3/2, day 22 n = 3/3). A significant difference was found at day 10 and day 22. * p = 0.034, ** p = 0.031. B) Splenocytes from mice receiving control diet or celecoxib diet were analyzed 10 days after tumour injection (n = 5/5). Subtypes were identified as described in Figure 1. A significant reduction was found in PMN-MDSC (p = 0.021) and in subset 2 from the Gr-1low MDSC population (p = 0.041) in mice receiving celecoxib diet. A significant increase was found in subset 1 from the Gr-1low MDSC population (p = 0.007), leading to a shift in ratio (p = 0.020) in celecoxib treated mice. The percentage of F4/80+MHCII+ cells was significantly reduced in mice receiving celecoxib diet (p = 0.022).