SERUM-SOLUBLE CD44 LEVELS FOR MONITORING DISEASE STATES IN ACUTE-LEUKEMIA AND MYELODYSPLASTIC SYNDROMES

To determine the clinical implications of soluble CD44 (sCD44) levels in hematologic neoplasias, we developed an enzyme-linked immunosobent assay for sCD44 using two monoclonal antibodies to the standard 90 kDa form, and assessed the serum concentration of sCD44 in normal healthy volunteers, patients with acute leukemia, myelodysplastic syndromes ( MDS), and those with chronic myeloid leukemia (CML). Compared to that in normal individuals (n=51; 145.1+/-24.6 ng/ml), the serum sCD44 leve l was significantly elevated in patients with acute myeloid leukemia ( AML; n=18; 331.9+/-99.0 ng/ml, P=0.0001), acute lymphoid leukemia (ALL ; n=16; 551.3+/-427.8 ng/ml, P=0.0001) and CML (n=18; 262.0+/-97.5 ng/ ml, P=0.0001). The sCD44 level was slightly elevated in patients with MDS (n=43; 173.8+/-54.9 ng/ml, P=0.0071). In patients with acute leuke mia, serum sCD44 concentrations decreased significantly in response to treatment and reached nearly normal levels after complete remission ( P=0.0005 in AML and P=0.0032 in ALL). The sCD44 levels in patients wit h MDS increased after they developed acute leukemia, whereas no signif icant difference in sCD44 levels was observed between the chronic and the blastic phases in patients with CML. Our results indicate that ser um sCD44 levels may be a useful marker for monitoring response to trea tment and disease progression, especially in acute leukemia.