OBJECTIVETo study the changes of soluble Apo-1/Fas levels in plasma, pleural and ascites fluid of malignant tumor patients and to evaluate their clinical significance.

METHODSThe soluble Apo-1/Fas levels were measured by enzyme-linked immunosorbent assay (ELISA) in the plasma of 157 malignant tumor patients and 25 normal controls as well as in the pleural and ascite fluids of 129 patients with various diseases.

RESULTThe plasma soluble Apo-1/Fas levels in acute and chronic leukemia and multiple myeloma were significantly higher than those in normal controls (P <0.05). The plasma soluble Apo-1/Fas levels in chronic myeloid leukemia and chronic lymphocytic leukemia were significantly higher than those in acute myeloid leukemia and acute lymphocytic leukemia, respectively (P <0.05). After chemotherapy, the plasma soluble Apo-1/Fas levels in complete remission group were distinctly decreased(P <0.05),whereas the levels in no remission and recurrence groups remained high. Compared with normal controls, the plasma soluble Apo-1/Fas levels in solid tumors were significantly increased (P <0.01), and the levels in metastasis cancers were significantly higher than those in non-metastasis cancer (P <0.0 1). Simultaneously the levels in remission cancer patients after operation and radiotherapy were distinctly lower than those before treatment(P <0.01), but were significantly increased in recurrence cancer patients (P <0.01). The soluble Apo-1/Fas levels in pleural and ascites fluid of malignant tumors were significantly higher than those in tuberculous effusions and transudates.

CONCLUSIONThe soluble Apo-1/Fas levels in plasma, pleural and ascites fluid of malignant tumor patients are markedly increased, which might be associated with the progress of cancers. The changes of soluble Apo-1/Fas levels may be useful for understanding the pathologic process of cancers and to differential diagnosis of various pleural and ascites fluids.