Detection of three sialylated tumor-associated antigens in malignant serous effusions

One hundred thirty-seven fluid samples from patients with malignant diseases, including 58 with lung cancer and 36 with gastric carcinoma, were screened for three tumor-associated carbohydrate antigens. The antigens tested were sialylated Lewis (SLEX) antigen, sialylated SSEA-1 (SLX) antigen, and sialylated Lewis (CA19-9) antigen. Thirty-four fluid samples from patients with benign diseases including 20 with tuberculous pleurisy were also tested for these three antigens as a control. SLEX antigen had the highest positivity rate among the three antigens both in the pleural effusions of patients with pulmonary adenocarcinoma and for all types of lung cancer (64.1% and 46.6%, respectively). In cancers of digestive system, the percentage of SLEX positivity was almost same as that for CA19-9, and higher than that for SLX. A combination assay using the three antigens resulted in an increased rate of detection of tumor-associated antigens (68% of 58 lung cancers including 83% of 39 adenocarcinomas, as well as 77% of 63 digestive system cancers including 84% of 36 gastric carcinomas). Gel filtration of pleural effusions or bile using sephacryl S-1000 showed that these three antigens were eluted in the void volume, indicating a molecular weight of greater than 2 X 10(6). Thus, all 3 antigens possibly exist on carrier protein with a high molecular weight. These observations suggest the potential application of these antigens to distinguish between benign and malignant fluid, and to monitor the effects of the treatment of various types of cancer.