This colorimetric assay quantitatively measures the

release of lactate dehydrogenase (LDH), a stable cytosolic enzyme. SB273005 in vivo Briefly, target cells were incubated in 96-well round bottom plates with learn more effector cells in 10:1, 5:1, 2,5:1 and 1,25:1 effector/target cell ratios for 4 h at 37°C. All samples were run in quadruplicate. Spontaneous release of effector or target cells was controlled by separate incubation of the respective population. At the end of incubation, the cells were lysed and centrifuged. 100 μl aliquot of each well was transferred into another 96 well plate and 100 μl of freshly “”LDH substrate solution”" was added to each well. The plates were incubated, light-protected, at room temperature for additional 10 min, and the reaction was stopped by the addition of acetic acid 1 M. The resulting light absorbance was measured in a microplate reader (Multiskan EX Labsystem) at 490 nm. The percentage of cytotoxic activity

was calculated according to the following formula: where Eexp LEE011 in vivo is the experimental LDH release of co-cultured effector and target cells, Esp and Tsp express the spontaneous released LDH of the effector and target cell alone, respectively, and Ttot is the maximum LDH amount of target cells. The LysiSpot assay The LysiSpot assay was set by a procedure similar to that of the ELISpot assay, with some modifications. In brief, polyvinylidene fluoride microtiter plates (MAIP S45 10,

Millipore Sunnyvale, CA, USA) were coated with capture MoAb against β-gal (from mouse fractionated ascites fluid, clone G4644 Sigma, Saint Louis, Missouri, USA) diluted at 12 μg/ml in PBS with 1% BSA. DHD-K12 target cells were plated 5 h after transfection at 1-4 × 104/well with effector cells (PBMC at 2 × 105/well) in complete RPMI medium and cultured for 16 h at 37°C in a 5% CO2. Biotinylated anti-β-gal detection MoAb (clone GAL 13 Sigma) diluted at 2 ug/ml in PBS with 1% BSA was added in a volume of 100 μl/well. After 90 min, avidin-horseradish peroxidase was added to the plates and incubated for 1 h incubation at r.t. (Pierce Biotechnology, Rockford, IL, USA). Plates were then washed and incubated with AEC-chromogen solution (BD Biosciences, Belgium) until red spots were clearly Glutamate dehydrogenase visible. Dual-colour LysiSpot assay Plates were coated with a mixture of capture MoAbs against β-gal and IFN-γ. Effector and target cells were prepared as in the LysiSpot assay (see above). After 16 h of incubation, Biotinylated anti-IFN-γ detection MoAb was added to the plates, followed by streptavidin-alkaline phosphatase conjugate. After washing, a 30 min, incubation with an unrelated biotinylated MoAb (we used MoAb anti-IL-4 diluted in RPMI) was performed to block any free streptavidin binding sites. Afterwards, the biotinylated β-gal detection MoAb was added to the plates, followed by avidin-horseradish peroxidase conjugate.