Abstract
We analyzed the immunosuppressive substance (IS) derived from malignant pleural effusion of lung cancer. This IS was different in molecular weight from any other immunosuppressive matter which has been reported, and the composition of amino acid was similar to α1-acid glycoprotein (α1-AG). The IS inhibited the blastogenesis of peripheral blood mononuclear cells from patients with lung cancer. This result suggests that IS plays a crucial role in immunosuppression in the patients with lung cancer.
