Granule Associated DNase in T-Lymphocytes from Patients with Inflammatory Disease

Abstract

Recent data highlight the undeniable role of programmed cell death type I of lymphocytes in the pathogenesis of certain allergic diseases and autoimmune diseases such as Bronchial Asthma and hemorrhagic rectocolitis. But little data exist on the enzymatic activity of secretory granules associated with lymphocytes of patients suffering from these inflammatory diseases. The aim of the study was to characterize the activity of the DNase in the secretory granules of T lymphocytes isolated from peripheral blood of patients with Bronchial Asthma (n = 20) and Hemorrhagic Rectocolitis (n = 20). Thus, the secretory granules were isolated from lymphocytes by the ultracentrifugation method on percoll density gradient. The detection of the activity of the protein extracts was performed by zymography and electrophoresis method. The results reveal the presence of a protein extract with a molecular weight of 66 kDa both at the level of the granules of the lymphocytes of patients suffering from hemorrhagic rectocolitis considered as a classical autoimmune disease and in the granules of lymphocytes of patients with Bronchial Asthma. The study of physicochemical properties showed an increase in the enzymatic activity of DNase of secretory granules when 1 mM Ca2+ was added to the incubation medium at a pH = 7.5. On the other hand, the addition of 1 mM Zn2 + causes the inhibition of enzyme activity. These results suggest that the enzymatic activity of DNase detected in the granule of lymphocytes of patients with Bronchial Asthma and hemorrhagic rectocolitis occurs not only in the fragmentation of double stranded DNA but could also play a role in the apoptotic process of these same T-lymphocytes. The study of the properties of this DNase in the inflammatory diseases could enable to use this protein as a marker for determining the severity of disease.