Leucocyte function in ulcerative colitis. Quantitative leucocyte mobilisation to skin windows and in vitro function of blood leucocytes.

Leucocyte function was evaluated by the in vivo mobilisation to skin windows with chambers and by the chemotactic, phagocytic, and nitro blue tetrazolium reducing capacity of blood leucocytes from 20 patients with ulcerative colitis. The total number of leucocytes mobilised to the chambers after 12 hours did not differ from those in 21 healthy volunteers. After 24 and 48 hours reduced number of leucocytes were mobilised by patients with ulcerative colitis (p less than 0.01). Correspondingly, the leucocyte migration rates were normal initially but were reduced after 18 hours Mobilisation in vivo was positively correlated to the blood neutrophil count (Rho:0.5549 po less than 0.02) but unrelated to clinical activity. Blood leucocytes showed reduced random migration in vitro as well as chemotactic response to casein (p less than 0.01). Serum independent and dependent phagocytosis did not differ from healthy volunteers. Nitro blue tetrazolium reduction by resting leucocytes was increased (p less than 0.01) in ulcerative colitis compared with controls. Our findings suggest altered in vivo mobilisation and in vitro migration of leucocytes in ulcerative colitis with increased spontaneous nitro blue tetrazolium reduction reflecting increased generation of potentially tissue damaging agents. The findings probably reflect changes secondary to the disease but which may be important in maintaining the inflammatory process.