title: High frequencies of naive Melan-A/MART-1-specific CD8(+) T cells in a large proportion of human histocompatibility leukocyte antigen (HLA)-A2 individuals.
abstract: Using fluorescent HLA-A*0201 tetramers containing the immunodominant Melan-A/MART-1 (Melan-A) tumor-associated antigen (Ag), we previously observed that metastatic lymph nodes of melanoma patients contain high numbers of Ag-experienced Melan-A-specific cytolytic T lymphocytes (CTLs). In this paper, we enumerated and characterized ex vivo Melan-A-specific cells in peripheral blood samples from both melanoma patients and healthy individuals. High frequencies (>/=1 in 2,500 CD8(+) T cells) of Melan-A-specific cells were found in 10 out of 13 patients, and, surprisingly, in 6 out of 10 healthy individuals. Virtually all Melan-A-specific cells from 6 out of 6 healthy individuals and from 7 out of 10 patients displayed a naive CD45RA(hi)/RO(-) phenotype, whereas variable proportions of Ag-experienced CD45RA(lo)/RO(+) Melan-A-specific cells were observed in the remaining 3 patients. In contrast, ex vivo influenza matrix-specific CTLs from all individuals exhibited a CD45RA(lo)/RO(+) memory phenotype as expected. Ag specificity of tetramer-sorted A2/Melan-A(+) cells from healthy individuals was confirmed after mitogen-driven expansion. Likewise, functional limiting dilution analysis and interferon gamma ELISPOT assays independently confirmed that most of the Melan-A-specific cells were not Ag experienced. Thus, it appears that high frequencies of naive Melan-A-specific CD8(+) T cells can be found in a large proportion of HLA-A*0201(+) individuals. Furthermore, as demonstrated for one patient followed over time, dramatic phenotype changes of circulating Melan-A-specific cells can occur in vivo.
authors.affiliation: Division of Clinical Onco-Immunology, Ludwig Institute for Cancer Research, Lausanne Branch, Centre Hospitalier Universitaire Vaudois, Switzerland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Pittet
authors.forename: D
authors.initials: D
authors.lastname: Valmori
authors.forename: P R
authors.initials: PR
authors.lastname: Dunbar
authors.forename: D E
authors.initials: DE
authors.lastname: Speiser
authors.forename: D
authors.initials: D
authors.lastname: Liénard
authors.forename: F
authors.initials: F
authors.lastname: Lejeune
authors.forename: K
authors.initials: K
authors.lastname: Fleischhauer
authors.forename: V
authors.initials: V
authors.lastname: Cerundolo
authors.forename: J C
authors.initials: JC
authors.lastname: Cerottini
authors.forename: P
authors.initials: P
authors.lastname: Romero
mesh_terms: D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D016022:Case-Control Studies; D015789:HLA-A2 Antigen / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis; D018655:Lymphocyte Count; D058965:MART-1 Antigen; D008545:Melanoma / Q000235:genetics / Q000276:immunology* / Q000556:secondary; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000276:immunology*; D010641:Phenotype; D011487:Protein Conformation; D013997:Time Factors
chemical_list: D000951:Antigens, Neoplasm; D015789:HLA-A2 Antigen; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D007371:Interferon-gamma