Prostate Tumor Immune Infiltrates Characterization

To characterize prominent prostate tumor infiltrates, we focused on abundant immunologic cell sub-types. We cut, stained and imaged archived formalin-fixed paraffin-embedded (FFPE) tumor tissue samples from the SCORE cases. Then we analyzed their cell type and count in the Department of Pathology and Laboratory Medicine at the University of Pennsylvania. Prostate sections from resected glands were stained for cytokeratin from tumor cells and T cells (CD3, CD8, FoxP3) and macrophages (CD68.) (Fig 1) The antibody clones that we used were CD3: clone LN 10 (Leica, catalog #NCL-L-3); CD8: clone C8/144B (DAKO, catalog #M7103); FOXP3: clone 206D (Biolegend, catalog #320102); and CD68: clone KP1 (DAKO, catalog #IR60961). The entire tumor nodule was scanned at low power to survey overall prevalence of infiltrating immune cells. We then selected 4 representative fields from each tumor sample. The area of the tumor that was selected depended on where the majority of cells were found in each tumor sample. Tissues were scored for infiltrating lymphocytes and macrophages in the dominant nodule (largest tumor nodule identified in the prostate) [21 (link)] by manually counting the number of TILs or TAMs in 4 fields at 20X for T cells and macrophages and averaging the scores.