A lectin with antiproliferative activity toward tumor cell lines and mitogenic activity toward splenocytes was isolated from the mushroom Polyporus adusta. The lectin was composed of two identical subunits each with a molecular weight of 12 kDa. It was adsorbed on both DEAE-cellulose and Q-Sepharose and unadsorbed on CM-Sepharose. The hemagglutinating activity of the lectin was inhibited by turanose and by a large variety of other carbohydrates. It was adversely affected in the presence of NaOH or HCl at a concentration of 7.5 mM and above, and when the ambient temperature was raised above 70degreesC. All divalent and trivalent metallic chlorides tested at 1.25-10 mM including CaCl2, MgCl2, ZnCl2, MnCl2, and AlCl3, did not alter the hemagglutinating activity of the lectin. FeCl3 at 10 mM caused the hemagglutinating activity to increase by 100%, but it did not change the lectin activity when tested at lower concentrations Lip to 5 mM. (C) 2003 Elsevier Inc. All rights reserved.