Development of granulocyte and monocyte adsorptive apheresis in the rat dextran sodium sulfate-induced colitis model.

Granulocytapheresis (GCAP) selectively removes large numbers of granulocytes and monocytes from peripheral blood by adsorptive apheresis, and in patients with ulcerative colitis GCAP has been associated with significant efficacy. However, the mechanism(s) of efficacy of this strategy is poorly understood. This rat model of dextran sodium sulfate (DSS)-induced colitis was to investigate the effect of GCAP on tumor necrosis factor (TNF)-alpha release by peripheral leukocytes. By using mini columns, an experimental GCAP setting was developed and applied to the DSS-induced colitis model. The production of TNF-alpha by lipopolysaccharide-activated leukocytes in whole blood was measured by enzyme-linked immunosorbent assay. In rats that received GCAP with columns containing leukocytapheresis carriers, TNF-alpha release by leukocytes was significantly (p < 0.05) suppressed, while no change in TNF-alpha production was seen in rats that received GCAP with sham columns. This first experimental setting in the rat colitis model suggests that GCAP is feasible in animals and should shed light on the mechanism(s) of GCAP in clinical settings. Given that TNF-alpha is a major inflammatory cytokine, down-modulation of TNF-alpha might represent one mechanism of antiinflammatory effects of GCAP.