title: Enzyme-linked immunospot assay for detection of human respiratory syncytial virus f protein-specific gamma interferon-producing T cells.
abstract: Respiratory syncytial virus (RSV) causes significant disease in elderly adults, and we have previously reported that individuals 65 years of age and older have reduced RSV F protein-specific gamma interferon (IFN-γ)-producing T cells compared to healthy younger adults. To measure RSV F-specific memory T cell responses in the elderly following infection or vaccination, we optimized and qualified an IFN-γ enzyme-linked immunospot (ELISPOT) assay. Since peripheral blood mononuclear cells (PBMC) from the elderly could be more fragile, we established optimal cryopreservation techniques and minimal viability acceptance criteria. The number of cells per well, types and concentrations of stimulation antigens, and incubation times were evaluated to maximize assay sensitivity and precision. The optimized assay uses 300,000 cells/well, 2 μg/ml of an RSV F peptide pool (RSV Fpp), and incubation for 22 ± 2 h in serum-free CTL-Test medium. The assay was qualified by 3 analysts using 3 RSV F-responding donor PBMC samples (high, medium, and low responders) tested on 5 different assay days. The assay sensitivity or limit of detection (LOD) was determined to be 21 spot-forming cells (SFC) per 10(6) PBMC, and the lower limit of quantitation (LLOQ) was estimated to be 63 SFC/10(6) PBMC. The intra- and interassay percent coefficients of variation (CV) were <10.5% and <31%, respectively. The results of the qualification study demonstrate that a robust, precise, and sensitive IFN-γ ELISPOT assay has been developed that is fit for measuring RSV F-specific IFN-γ T cell responses in subjects enrolled in a vaccine clinical trial or in epidemiology studies.
authors.affiliation: Infectious Diseases/Vaccines Research, MedImmune, LLC, Mountain View, California, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Patton
authors.forename: Shahin
authors.initials: S
authors.lastname: Aslam
authors.forename: Jim
authors.initials: J
authors.lastname: Lin
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Stacie
authors.initials: S
authors.lastname: Lambert
authors.forename: Glenn
authors.initials: G
authors.lastname: Dawes
authors.forename: Mark T
authors.initials: MT
authors.lastname: Esser
authors.forename: Jennifer
authors.initials: J
authors.lastname: Woo
authors.forename: Sylvia
authors.initials: S
authors.lastname: Janetzki
authors.forename: Anu
authors.initials: A
authors.lastname: Cherukuri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002478:Cells, Cultured; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D011309:Preservation, Biological; D015203:Reproducibility of Results; D018113:Respiratory Syncytial Virus, Human / Q000276:immunology*; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology*; D014760:Viral Fusion Proteins / Q000276:immunology*; D055815:Young Adult
chemical_list: C526850:F protein, human respiratory syncytial virus; D014760:Viral Fusion Proteins; D007371:Interferon-gamma