title: Evaluation of antigen specific recognition and cell mediated cytotoxicity by a modified lysispot assay in a rat colon carcinoma model.
abstract: BACKGROUND
  Antigen-specific CD8+ cytotoxic T lymphocytes represent potent effector cells of the adaptive immune response against viruses as well as tumours. Therefore assays capable at exploring the generation and function of cytotoxic T lymphocytes represent an important objective for both clinical and experimental settings.
  
  
  METHODS
  Here we show a simple and reproducible assay for the evaluation of antigen-specific CD8+ cytotoxic T lymphocytes based on a LysiSpot technique for the simultaneous determination of antigen-specific IFN-γ production and assessment of tumor cytolysis. The assay was developed within an experimental model of colorectal carcinoma, induced by the colorectal tumor cell line DHD-K12 that induces tumors in BDIX rats and, in turn, elicits a tumor- specific immune response.
  
  
  RESULTS
  Using DHD-K12 cells transfected to express Escherichia coli β-galactosidase as target cells, and by the fine setting of spot colours detection, we have developed an in vitro assay that allows the recognition of cytotoxic T lymphocytes induced in BDIX rats as well as the assessment of anti-tumour cytotoxicity. The method highlighted that in the present experimental model the tumour antigen-specific immune response was bound to killing target cells in the proportion of 55%, while 45% of activated cells were not cytotoxic but released IFN-γ. Moreover in this model by an ELISPOT assay we demonstrated the specific recognition of a nonapeptide epitope called CSH-275 constitutionally express in DHD-K12 cells.
  
  
  CONCLUSIONS
  The assay proved to be highly sensitive and specific, detecting even low frequencies of cytotoxic/activated cells and providing the evaluation of cytokine-expressing T cells as well as the extent of cytotoxicity against the target cells as independent functions. This assay may represent an important tool to be adopted in experimental settings including the development of vaccines or immune therapeutic strategies.
authors.affiliation: Laboratory of Clinical Pathology and Microbiology, San Gallicano Dermatologic Institute, Via Elio Chianesi, 53, 00144 Rome, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Bordignon
authors.forename: Paola
authors.initials: P
authors.lastname: Cordiali-Fei
authors.forename: Monica
authors.initials: M
authors.lastname: Rinaldi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Signori
authors.forename: Andrea
authors.initials: A
authors.lastname: Cottarelli
authors.forename: Manuela
authors.initials: M
authors.lastname: Zonfrillo
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Ensoli
authors.forename: Guido
authors.initials: G
authors.lastname: Rasi
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Fuggetta
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000276:immunology*; D004195:Disease Models, Animal; D000939:Epitopes / Q000276:immunology* / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism*; D009374:Neoplasms, Experimental / Q000276:immunology*; D051381:Rats; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000939:Epitopes; D007371:Interferon-gamma