PHENOTYPIC STABILITY OF A CYTOTOXIC T-CELL LINE DIRECTED AGAINST AN IMMUNODOMINANT EPITOPE OF HUMAN CARCINOEMBRYONIC ANTIGEN

CTL lines have now been generated against defined peptides of a range of human tumor-associated antigens (TAAs), One of the potential uses o f these epitope-specific CTLs is in adoptive transfer immunotherapy. T his is a modality, however, that will require long-term in vitro cultu re of CTLs, To date, little has been reported concerning the phenotypi c stability of human epitope-specific CTLs as a consequence of long-te rm in vitro propagation via peptide stimulation, We report here the se rial phenotypic characterization of a CTL line directed against an imm unodominant epitope (YLSGANLNL, designated CAP-1) of human carcinoembr yonic antigen (CEA), This CTL line was derived from peripheral blood m ononuclear cells of a patient with metastatic carcinoma who had been t reated with a recombinant CEA-vaccinia vaccine in a Phase I trial; the CTLs were analyzed through 20 in vitro cycle passages of stimulation with CAP-1 peptide and interleukin 2 in the presence of autologous ant igen-presenting cells, The CTL line was shown to be phenotypically sta ble in terms of high levels of cytokine (IFN-gamma, tumor necrosis fac tor, and granulocyte-macrophage colony-stimulating factor) production, expression of homing-adhesion molecules, ability to lyse peptide-puls ed targets, and ability to lyse human carcinoma cells endogenously exp ressing CEA in a MHC-restricted manner, V beta T-cell receptor gene us age was also analyzed, These studies thus present a rationale for the use of longterm cultured epitope-specific human CTLs, directed against a human TAA for potential adoptive transfer immunotherapy protocols.