The Prognostic Significance of Tumor-Infiltrating Lymphocytes
Tumors have been known to contain variable numbers of lymphocytes, referred to as tumor infiltrating lymphocytes (TILs). The degree of the lymphocytic infiltrate has been shown to correlate with positive outcome in some types of cancers. However, there are conflicting reports regarding the prognosis value of TIL even with the same types of cancers. Much research has gone into classifying TILs with respect to antigen receptor structure and the antigen to which the tumor-specific T cells react. However, these studies for the most part did not immunophenotype TILs, and recent data has revealed that the composition of TIL is not homogenous, but rather represents varying contributions from many lymphocytic subsets. Furthermore, the function of TILs is often compromised as a result of the accumulation of immunoregulatory cells and various tumor escape mechanisms. These recent findings stress the need to collect more data on the composition and function of TIL infiltrates before definitive conclusions about the prognostic significance of TILs can be drawn. This chapter summarizes the functional significance of different subsets of lymphocytes infiltrating the tumors.
KeywordsMajor Histocompatibility Complex Class Adoptive Transfer Antitumor Immunity Tumor Immunity Primary Cutaneous Melanoma
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