ABSTRACT
This chapter reviews the functional and phenotypic characteristics of tumor infiltrating lymphocytes (TIL) obtained from human solid tumors. Both immunofluorescence and immunoperoxidase techniques have been extensively applied to the examination of TIL in a variety of human solid tumors. In spite of the difficulties, TIL have been isolated from numerous human tumors of different histologic types and evaluated for their functional responses in vitro. The simultaneous performance of immunohistology and analysis of cells in suspension by flow cytometry assures the most accurate phenotypic evaluation of TIL, but even then it is necessary to consider a sampling error, since the analyzed tumor portion may not accurately represent the entire cellular content of the tumor. Phenotypic and functional studies of TIL isolated from tumor biopsies and separated on density gradients are not only technically difficult, but fraught with errors. To date, rIL-2 in relatively high concentrations has proven to be the best exogenous agent for activation of TIL from human tumors.
