title: Characterization of CD8(-) HLA class I/epitope tetrameric complexes binding T cells.
abstract: Antigen-specific CD8-expressing T cells play a crucial role in the host's defense against viral disease and malignancy. Epitope-specific CD8(+)T cell responses to malignant and viral disease can be accurately measured using tetramers (tHLA) of HLA class I molecules loaded with antigenic peptides. In addition, tHLA have been used to evaluate immune responses to antigen-specific immunization. tHLA bind specifically to complementary T-cell receptor (TCR) structures on the surface of T cells expressing the CD8 coreceptor. Surprisingly, however, CD8(-) cells binding tHLA are often observed. This study uses four-color flow cytometry to show that HLA-A*0201-tHLA-stained CD8(-) cells can be divided into two subsets: 87% represent B-lymphocytes (CD19(+), CD45RA(+), HLA-DR(+), and CD20(+)), and 13% represent T-helper cells (CD3(+), CD4(+), CD45RA(+), and CD27(+)). This phenomenon is not HLA-restricted because it could be observed even in peripheral blood mononuclear cells (PBMC) from a non HLA-A*0201-expressing healthy donor. In addition, no T-cell receptor was detected on the B-lymphocytes. Retrospective enumeration of vaccine-induced CD8(-) tHLA cells in 243 PBMC samples from 36 patients with melanoma undergoing peptide vaccination revealed that tHLA staining is not dependent on immunization status or the presence of CD8(+) tHLA(+) T cells. These findings, suggest that the nonspecific binding of tHLA to non-TCR-expressing T cells requires a careful interpretation of results and further steps in preparation of sample for tHLA-based sorting of epitope specific T cells.
authors.affiliation: Immunogenetics Section, Department of Transfusion Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland 20982-1502, USA.
authors.forename: Dirk
authors.initials: D
authors.lastname: Nagorsen
authors.forename: Vladia
authors.initials: V
authors.lastname: Monsurrò
authors.forename: Ena
authors.initials: E
authors.lastname: Wang
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Marincola
mesh_terms: D019496:Cancer Vaccines / Q000627:therapeutic use; D016022:Case-Control Studies; D000939:Epitopes / Q000737:chemistry / Q000378:metabolism; D006680:HLA Antigens / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008545:Melanoma / Q000276:immunology / Q000628:therapy; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D019496:Cancer Vaccines; D000939:Epitopes; D006680:HLA Antigens; D046911:Macromolecular Substances