Dipeptidyl peptidase IV in patients with systemic lupus erythematosus.

The activity of dipeptidyl peptidase IV (DPP IV) was measured in the serum and peripheral blood mononuclear cells (MNC) of patients with systemic lupus erythematosus (SLE). The number of DPP IV positive (DPP IV+) lymphocytes in blood smears was determined cytochemically in groups of patients with active, moderate and inactive disease. Compared with healthy subjects, serum DPP IV activity was significantly decreased regardless of the level of disease activity. DPP IV activity in MNC was markedly decreased only in the patients with the active disease. Moreover, marked differences in the number of DPP IV+ lymphocytes could be detected between the groups of patients with the inactive and/or moderately active forms of the disease and those with active disease. The percentages of DPP IV+ lymphocytes, as well as DPP IV activity in MNC, showed significant correlations with the percentages of E-rosetting cells. Evaluation of DPP IV in SLE patients represents a new approach in the study of the pathological process of this disease.