Chitotriosidase, a macrophage marker, which is extremely increased in plasma of Gaucher patients, was measured in patients with
beta-thalassemia, an haematological disorder characterized by the genetic defect of
beta-globin chains synthesis resulting in unproductive erythropoiesis and enormous expansion of the reticuloendothelial system. Plasma
chitotriosidase was increased to a variable extent in 13 of 70 patients with
beta-thalassemia major treated with the intense transfusion regimen and
iron chelation therapy. It was normal in 22 and slightly elevated in 3 subjects with
beta-thalassemia intermedia which were not transfused. The highest levels of plasma
chitotriosidase, as high as in Gaucher patients, 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 level (> 3000 ng/ml), high
SGPT level and elevated urinary
iron excretion. To our knowledge,
beta-thalassemia is hitherto the only disorder in which an increase of plasma
chitotriosidase, comparable to that seen in
Gaucher disease, may occur. The increase of plasma
chitotriosidase activity in
beta-thalassemia patients with high
iron overload, could be related to an
iron mediated damage to the lysosomal apparatus. In addition, similarly to
Gaucher disease, the increased
chitotriosidase production in
beta-thalassemia might reflect macrophage activation probably related to the intracellular
iron overload, storage of erythrocytes membrane break-down products and oxidation of excess alpha-
hemoglobin subunits. Further studies are required to define the role of
chitotriosidase evaluation to assess the efficacy of
chelation therapy in reducing the macrophage activation due to intracellular
iron overload in
beta-thalassemia.