The Effects of Dextrose and Mannitol on TNF-α Production From LPS-Stimulated Feline PBMC
High glucose concentration and osmolality have been shown to alter tumor necrosis factor (TNF)-α production from human peripheral blood mononuclear cells (PBMC). The objective of this study was to evaluate the effect of dextrose and mannitol on lipopolysaccharide (LPS)-induced TNF-α production from feline PBMC. Blood was collected from 4 adult cats and PBMC were harvested immediately using a histopaque technique. Cellular viability was assessed using trypan blue exclusion. Cell counts were normalized to 2 x 106 cells/well in RPMI, horse serum, penicillin and streptomycin. The cells were incubated at 37o C in either culture media alone (control), dextrose 600 mg/dl (HD), dextrose 400 mg/dl (MD), mannitol 600 mg/dl (HM) or mannitol 400 mg/dl (MM) for 24 hours. Then, LPS (25 ng/ml or 50 ng/ml) was added to the media. At 48 hours, cell culture supernatant was collected and TNF-α activity quantified using a cell killing bioassay. Data were analyzed using an ANOVA and post-hoc Fisher LSD method with a p-value of <0.05 considered significant. LPS induced significantly increased cell culture supernatant mean±SD TNF-α activity (50 ng/ml, 844±936; 25 ng/ml, 458±379; 0 ng/ml, 164±258 pg/ml; p<0.001) in a dose dependent manner regardless of treatment. TNF-α activity was significantly greater in the cell culture supernatant from the PBMC incubated with HM (717±62 pg/ml) than supernatant from PBMC incubated with HD (396±62 pg/ml, p=0.005), MD (382±73 pg/ml; p=0.007) or control (331±214 pg/ml, p<0.001). In this study, mannitol had a greater pro-inflammatory effect on LPS stimulated feline PBMC than dextrose, ex vivo.