Abstract
We assessed the activity of rnethyltransferase and phospholipase A2 which often induce cell activation, ethanolaminephosphotransferase (EPT) and cholinephosphotransferase (CPT) which mediate the constituent of structural phospholipids of phosphatidylethanolamine (PE) and phosphatidylcholinc (PC), and base-exchange reactions whose biological and physiological significance has not been clarified, in 36 patients with various inflammatory disorders. In the membranes of both neutrophils and lymphocytes from the patients with Behçet's disease, SLE, RA (in active stages) and severe bacterial infections, methyltransferase and phospholipase A2 activities and ethanolaminc-base exchange activity were markedly or significantly enhanced. In the patients with severe viral infections, only an increase in phospholipase A2 activity of lymphocyte membrane was observed. On the other hand, EPT and CPT activities, and serine and cholinebase exchange activities were not significantly changed although choline-exchange activity showed trends to decrease in the leukocyte membranes from the patients who showed the enhancement of ethanolamine-exchange. This study postulates that cthanolamme-exchange activity whose mechanism has not been known may be a precursor for the formation of PE which leads to the cell activation by the production of arachidonic acid (AA cascade) induced by mediation of transmethylation and phospholipase A2 activity.
