FREQUENCY AND RELATIVE FRACTION OF TUMOR ANTIGEN-SPECIFIC T-CELLS AMONG LYMPHOCYTES FROM MELANOMA-INVADED LYMPH-NODES

Several tumor antigens have been described as candidates for immunothe rapy, Our study compared HLA-A2-restricted epitopes from 5 antigens co mmonly expressed by melanomas, i.e,, Melan-A/MART-1 peptides(26-35 and 27-35), tyrosinase (368-376), gp-100 (280-288), MAGE-3 (271-279) and NA17-A (1-10), for their relative capacity to promote the development of cytotoxic and cytokine-producing specific CD8(+) lymphocytes within melanoma-invaded lymph nodes. We used short-term cultured melanoma-in vaded lymph node lymphocytes (MILLs) and tested responses developed by these cells to peptide-pulsed TAP-deficient T2 cells. We measured bot h the lytic response developed by MILLs and the fraction of these cell s that secreted interferon-gamma (IFN-gamma), as deduced from intracel lular cytokine labeling. Reverse transcription-polymerase chain reacti on (RT-PCR) was used to analyze the expression of the 5 antigens withi n melanomainvaded lymph nodes. Melan-A/MART-1, tyrosinase and gp-100 p eptides were recognized by MILLs derived, respectively, from 8 of 20, 5 of 19 and 4 of 20 melanoma-invaded lymph nodes expressing these anti gens, Most MILLs specific for Melan-A/MART-1 and tyrosinase exhibited both lysis and IFN-gamma responses, whereas most of those specific for gp-100 developed only lysis. Weak lysis without IFN-gamma secretion w as developed against NA17-A and MAGE-3 peptides by MILLs from, respect ively, 3 of 9 and 2 of 14 lymph nodes expressing these antigens, Our d ata show a prevalence of both cytotoxic and IFN-gamma-secreting effect or T cells specific for differentiation antigens within HLA-AZ melanom a-invaded lymph nodes, which makes these antigens attractive targets f or specific immunotherapy. (C) 1998 Wiley-Liss, Inc.