1. Geographic distribution in situ of MSI and MSS colorectal cancer–infiltrating lymphocytes.
Geographic distribution in situ of MSI and MSS colorectal cancer–infiltrating lymphocytes. Formalin-fixed, paraffin-embedded tissue sections were characterized by IHC for CD4+, CD8+, and FOXP3+ cell infiltration. Three distinct histologic areas designated as TIL, tumor stroma, and invasive front (where tumor invaded normal lamina propria) were histologically identified and separately analyzed. Invasive front (A) and TIL/stroma (B) areas of representative MSS (bottom) and MSI (top) specimens are shown (×20 magnification). Dashed lines in A delineate the invasive front with the tumor tissue on the top side and the normal tissue on the bottom side. Red stars and blue arrows in B indicate the tumor stroma and tumor epithelium-infiltrating immune cells, respectively. Scale bars, 100 μm. C, cell density was scored in 14 MSS (blue) and 9 MSI (red) specimens by determining the average number of stained cells in 5 distinct hpf ( mm2/hpf). The graphs display the mean for each group; *,statistically significant differences between MSS and MSI (P < 0.05, using Mann–Whitney U test).
Nicolas J. Llosa et al. Cancer Discovery 2015;5:43-51
©2015 by American Association for Cancer Research