LFA-1 subunit expression in ulcerative colitis patients.

The adhesion molecule, lymphocyte function associated antigen (LFA-1) consisting of two subunits, CD11a and CD18, mediates lymphocyte migration into tissue and cell effector functions. Previous observations showed no differences in LFA-1 expression by circulating lymphocytes between inflammatory bowel disease patients and controls. The aim of the present work was to study subsets of circulating LFA-1+ lymphocytes in ulcerative colitis (UC) patients versus healthy controls. Peripheral blood mononuclear cells were obtained from 16 UC patients and 10 healthy volunteers. The percentages of CD11alo, CD11ahi, CD18lo, CD18hi T and B cells, as well as Cd25 expression on these cells were studied using double staining with monoclonal antibodies and panning procedures. The percentage of CD11hi and CD18hi T cells was significantly decreased in quiescent UC patients as compared to active disease patients and healthy controls (P < 0.05). The majority of CD25+ T cells were expressing CD11a and CD18 with low density. A detectable percentage, 2% (range 1-6%), of CD11ahiCD25+ (but not CD18hiCD25+) was found in UC patients with moderate to severe disease, but not in those with inactive UC to healthy controls. In conclusion, the percentage of CD11ahi+ and CD18hi+ T cells is decreased in peripheral blood of quiescent UC patients, which is probably associated with the effect of specific treatment. The percentage of CD11ahi+IL-2R alpha+ T cells is increased in peripheral blood of patients with active (moderate and severe) UC, which most likely reflects a sustained T-cell activation due to a persistent inflammatory process.