title: HLA class II-restricted CD4+ T cell responses directed against influenza viral antigens postinfluenza vaccination.
abstract: The memory T cell response is polyclonal, with the magnitude and specificity of the response controlled in part by the burst size of T cells expanded from effector/memory precursors. Sensitive assays using HLA class II multimers were used to detect low-frequency Ag-specific T cells directed against influenza viral Ags in subjects immunized with the influenza vaccine. Direct ex vivo tetramer staining of PBMC from five individuals identified frequencies of hemagglutinin (HA) 306-318 tetramer binding CD4(+) T cells in the peripheral blood ranging from 1 in 600 to 1 in 30,000 CD4(+) T cells. These frequencies were validated by counting CFSE(low), tetramer-positive T cells after in vitro expansion. Low frequency of T cells directed to other influenza epitopes, including DRA1*0101/DRB1*0401-restricted matrix protein 60-73, DRA1*0101/DRB1*0101-restricted matrix protein 18-29, DRA1*0101/DRB1*0701-restricted HA 232-244 and DRA1*0101/DRB1*0101-restricted nucleoprotein 206-217 were also determined. T cells which occurred at a frequency as low as 1 in 350,000 could be ascertained by in vitro expansion of precursors. Peripheral HA(306-318)-responsive T cells expanded 2- to 5-fold following influenza vaccination. Examination of phenotypic markers of the HA(306-318)-responsive T cells in the peripheral blood indicated that the majority were CD45RA(-), CD27(+), CD25(-), CD28(+), and CD62L(-), while T cell clones derived from this population were CD45RA(-), CD27(-), CD25(+), CD28(+), and CD62L(-).
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA 98101, USA.
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Danke
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
mesh_terms: D000595:Amino Acid Sequence; D000956:Antigens, Viral / Q000097:blood / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000276:immunology* / Q000821:virology*; D002999:Clone Cells; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay; D018984:Epitopes, T-Lymphocyte / Q000097:blood / Q000276:immunology; D005452:Fluoresceins / Q000032:analysis; D006684:HLA-DR Antigens / Q000276:immunology*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000097:blood / Q000276:immunology; D006801:Humans; D007115:Immunization Schedule; D016130:Immunophenotyping; D009980:Influenza A virus / Q000276:immunology; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000032:analysis / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000821:virology; D018655:Lymphocyte Count; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000097:blood / Q000276:immunology; D013194:Staining and Labeling; D013388:Succinimides / Q000032:analysis
chemical_list: C087165:5-(6)-carboxyfluorescein diacetate succinimidyl ester; D000956:Antigens, Viral; D018984:Epitopes, T-Lymphocyte; D005452:Fluoresceins; D006684:HLA-DR Antigens; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D010446:Peptide Fragments; D013388:Succinimides