Fig 3 Immunologic monitoring approaches. Summary of the processing of patient specimens and the immune monitoring assays. Tumors can be frozen or formalin fixed and paraffin embedded and slices tested by immunohistochemistry (IHC). They can also be enzymatically digested into viable single cell suspensions. Blood can be separated using density gradient centrifugation (Ficoll-Paque) and a variety of tests performed; TIL=tumor infiltrating lymphocyte