Leukocytapheresis therapy modulates circulating T cell subsets in patients with ulcerative colitis

The aim of this study was to elucidate the molecular mechanisms responsible for the therapeutic effects of leukocytapheresis (LCAP). We investigated the alterations in circulating T cell subsets after LCAP therapy in ulcerative colitis (UC) patients. Eighteen patients with UC were enrolled. Fourteen patients were responders, and four patients were non-responders. Peripheral venous blood was obtained within 5 min before and 5 min after LCAP therapy. Flow cytometric analysis for T cell markers and intracellular interferon (IFN)-gamma (Th1) and interleukin (IL)-4 (Th2) was then performed. The average numbers of lymphocytes, T and B cells were significantly decreased after LCAP therapy, respectively (P < 0.01). The numbers of CD4(+) and CD8(+)T cells were also significantly decreased, respectively (P < 0.01), but the CD4(+)/CD8(+) ratio was not changed. The number of CD45RO(+)CD4(+) memory T cells was significantly decreased. The number of CD25(+)CD4(+) T cells tended to decrease after LCAP therapy (not significant). However, the ratio of CD25(+)CD4(+)-cells/CD25(-)CD4(+)-cells was significantly increased (P < 0.05). The number of IFN-gamma-positive (Th1) cells was significantly decreased after LCAP therapy, but there was no significant change in the number of IL-4-positive (Th2) cells. The Th1/Th2 ratio was significantly decreased after LCAP therapy. Some of the immuno-suppressive effects of LCAP therapy may be associated with a modulation of circulating T cell subsets.