Proliferation Assay
CCO cells were seeded at 0.8x104 cells per well on a black 96 well plate with optical bottom (Thermo Scientific) in L-15 with 1% FBS 100μl. Following adherence, cells were treated with varying concentrations of cfIL-22 or pBK empty vector control (negative) for 24 hours. Resazurin sodium salt (0.15mg/mL; Sigma) was dissolved into DPBS (pH 7.4, Corning, Fisher Scientific), sterilized through a 0.2µm filter and stored at 4°C for up to two weeks in a light protected container. Resazurin (20 μl) was added to each well and incubated for 3 hours at 28°C. Fluorescence was read using a Biotek Synergy 2 plate reader (Excitation 560nm/emission 590nm). Data are analyzed in Microsoft Excel and reported as relative fluorescent units.