TILs are typically detected through the examination of hematoxylin and eosin (H&E) stained tissue sections using light microscopy. Pathologists assess the density and distribution of TILs within both the tumor stroma and the cancer cell nests. Additionally, immunohistochemistry (IHC) can be employed to identify specific subsets of TILs, such as CD3+ T cells, CD8+ cytotoxic T cells, and CD20+ B cells.
