Plasma chitotriosidase activity in patients with beta-thalassemia

Chitotriosidase, a macrophage marker, which is extremely increased in plasm a of Gaucher patients, was measured in patients with beta-thalassemia, an h aematological disorder characterized by the genetic defect of beta-globin c hains synthesis resulting in unproductive erythropoiesis and enormous expan sion of the reticuloendothelial system, Plasma chitotriosidase was increase d to a variable extent in 13 of 70 patients with beta-thalassemia major tre ated with the intense transfusion regimen and iron chelation therapy, It wa s normal in 22 and slightly elevated in 3 subjects with beta-thalassemia in termedia which were not transfused. The highest levels of plasma chitotriosidase, as high as in Gaucher patient s, were found in 7 (10%) of the beta-thalassemia major patients which also had the highest degree of iron overload as judged by their serum ferritin l evel (> 3000 ng/ml), high SGPT level and elevated urinary iron excretion, To our knowledge, beta-thalassemia is hitherto the only disorder in which a n increase of plasma chitotriosidase, comparable to that seen in Gaucher di sease, may occur, The increase of plasma chitotriosidase activity in beta-t halassemia patients with high iron overload, could be related to an iron me diated damage to the lysosomal apparatus. In addition, similarly to Gaucher disease, the increased chitotriosidase production in beta-thalassemia migh t reflect macrophage activation probably related to the intracellular iron overload, storage of erythrocytes membrane break-down products and oxidatio n of-excess alpha-hemoglobin subunits, Further studies are required to defi ne the role of chitotriosidase evaluation to assess the efficacy of chelati on therapy in reducing the macrophage activation due to intracellular iron overload in beta-thalassemia, (C) 1998 Academic Press.