title: Natural antigenic peptides from squamous cell carcinoma recognized by autologous HLA-DR8-restricted CD4+ T cells.
abstract: A large number of human tumor antigens recognized by CD8+ cytotoxic T lymphocytes (CTL) have been identified. Some of them have been employed in clinical trials and have achieved some objective responses. However, little is known about those that are recognized by CD4+ T cells, except for a very few that were identified from melanomas. Previously, we reported that an oral squamous cell carcinoma (SCC) cell line, OSC-20, was effectively lysed by HLA-DRB1*08032 (HLA-DR8)-restricted autologous CD4+ T cell line, TcOSC-20. In this study, we performed two steps of chromatographic purification of the tumor cell lysate in combination with mass spectrometry. We found one reverse-phase high-performance liquid chromatography (RP-HPLC) fraction that was effectively recognized by the T cells. We analyzed the fraction by nano-liquid chromatography/electrospray ionization ion trap mass spectrometry (LC/MS/MS) and found six representative ions. We could determine the primary amino acid sequence of each of the six ions. Three of them contained a potential HLA-DR8 binding motif, and TcOSC-20 showed a rather strong cytotoxic response to one of the synthetic peptides, namely, amino acid residues 321-336 of human alpha-enolase. Thus, several gene products of squamous cancer cells are endogenously processed and may be presented on HLA class II molecules, so that they could constitute target molecules for autologous CD4+ T cells.
authors.affiliation: Department of Pathology, Sapporo Medical University School of Medicine, Chuo-ku, Sapporo 060-8556, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kondo
authors.forename: Hiroeki
authors.initials: H
authors.lastname: Sahara
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nabeta
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Hirohashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kanaseki
authors.forename: Akira
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yamada
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hirayama
authors.forename: Manabu
authors.initials: M
authors.lastname: Suzuki
authors.forename: Junji
authors.initials: J
authors.lastname: Hamuro
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Torigoe
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Gen-iku
authors.initials: GI
authors.lastname: Kohama
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ikeda
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Sato
mesh_terms: D020816:Amino Acid Motifs; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006684:HLA-DR Antigens / Q000378:metabolism*; D059810:HLA-DR Serological Subtypes; D006801:Humans; D007477:Ions; D010455:Peptides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014407:Tumor Cells, Cultured
chemical_list: D006684:HLA-DR Antigens; D059810:HLA-DR Serological Subtypes; C041559:HLA-DR8 antigen; D007477:Ions; D010455:Peptides