title: Enhanced ELISPOT detection of antigen-specific T cell responses from cryopreserved specimens with addition of both IL-7 and IL-15--the Amplispot assay.
abstract: The importance of the enzyme-linked immunosorbent spot (ELISPOT) assay as a tool for studying immune responses in vitro is becoming increasingly apparent. However, there remains a need for enhanced sensitivity for the detection of low frequency antigen-specific T cell responses. We reasoned that the addition of a combination of the cytokines interleukin (IL)-7 and IL-15 would selectively increase interferon-gamma (IFN-gamma) production from antigen-stimulated CD4+ and CD8+ effector memory T cells. Freshly isolated or cryopreserved peripheral blood mononuclear cells (PBMC) from four healthy donors were analysed by ELISPOT for the frequency of purified protein derivative (PPD)-specific CD4+ T cells or cytomegalovirus (CMV) peptide-specific CD8+ T cells. Addition of IL-7 and IL-15 increased the number of PPD-specific CD4+ T cells up to 2.4-fold in fresh PBMC and up to 18-fold in cryopreserved PBMC. The cytokines also increased the number of CMV peptide-specific CD8+ T cells in fresh PBMC up to 7.5-fold. No additional increases were seen when antibodies to co-stimulatory molecules CD28 and CD49d were applied together with the cytokine combination. These data demonstrate that the sensitivity of the ELISPOT assay may be significantly augmented by addition of the cytokines IL-7 and IL-15 to antigen-stimulated cells. This method will be particularly useful for the assessment of antigen-stimulated cytokine production by T cells in cryopreserved biological specimens.
authors.affiliation: Gladstone Institute of Virology and Immunology, University of California-San Francisco, San Francisco, CA, USA. wjennes@itg.be
authors.forename: Wim
authors.initials: W
authors.lastname: Jennes
authors.forename: Luc
authors.initials: L
authors.lastname: Kestens
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Nixon
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Shacklett
mesh_terms: D000941:Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D015925:Cryopreservation; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards; D015683:Gene Products, gag / Q000276:immunology; D015684:Gene Products, pol / Q000276:immunology; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000378:metabolism; D019409:Interleukin-15 / Q000008:administration & dosage / Q000276:immunology*; D015851:Interleukin-7 / Q000008:administration & dosage / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D010455:Peptides / Q000276:immunology; D010750:Phosphoproteins / Q000276:immunology; D014373:Tuberculin / Q000276:immunology; D014763:Viral Matrix Proteins / Q000276:immunology
chemical_list: D000941:Antigens; D015683:Gene Products, gag; D015684:Gene Products, pol; D019409:Interleukin-15; D015851:Interleukin-7; D010455:Peptides; D010750:Phosphoproteins; D014373:Tuberculin; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D007371:Interferon-gamma