Number of activated T-helper cells and NK cells in peripheral blood is decreased in severe Crohn's disease.

Monoclonal antibodies and flow cytometry were used to analyse the proportions of T-cell subsets and NK cells in blood of patients (n = 45) with Crohn's disease. In patients with severe activity disease decreased numbers of activated (CD25+CD4+) T-helper cells and NK (CD16+CD56+) cells were found, while in patients with low activity disease the numbers of activated T-helper cells were increased and the numbers of NK cells were similar to those in normal controls. Thus, 8% of T cells were CD25+CD4+ and 16% of mononuclear cells were CD16+CD56+ in patients with severe disease. In patients with quiescent disease, 11% of T cells were CD25+CD4+ and 26% of mononuclear cells were CD16+CD56+. The results suggest that disease activity may be reflected in the proportions of blood circulating mononuclear cells, perhaps because of accumulation of CD25+CD4+ T-helper cells and NK cells in the affected tissue during exacerbation of the disease.