Comprehensive analysis of the frequency of recognition of melanoma-associated antigen (MAA) by CD8 melanoma infiltrating lymphocytes (TIL): implications for immunotherapy

International audienceFifty-nine tumor-infiltrating lymphocyte (TIL) cultures established from melanoma-invaded lymph nodes were screened for recognition of 28 melanoma-associated antigens (MAA) in association with 31 HLA molecules. Twenty-three (39%) TIL lines reacted to at least one mel-anoma antigen. Melanosomal proteins were recognized by 19 TIL populations and the most prominent responses against these proteins were directed against Melan-A/MART-1 (mainly in association with HLA-A*0201) and gp100 (in association with diverse HLA contexts). Ten TIL populations reacted against 10 tumor-specific antigens, in association with 8 different HLA molecules. HLA-A*0201 and B*3501-restricted responses were the most frequent with, respectively, 17 and 7 responses directed against 5 distinct antigens. Unexpectedly, the recognition by TIL of different MAA was frequently restricted by a single HLA in individual tumors, and there was no evidence for the existence of dominant MAA epitopes between tumors, except for Melan-A/MART-1 antigen. This analysis also led to the detection of 21 new HLA-peptide complexes recognized by melanoma TIL. This study, which is to our knowledge the most comprehensive analysis of TIL specificity to tumor antigens, has several implications for the design of immunotherapeutic strategies based on immunization against selected tumor epitopes