From the dried fruiting bodies of the Mushroom Armillaria luteo-virens, a dimeric lectin with a molecular mass of 29.4 kDa has been isolated. The purification procedure involved (NH4)(2)SO4 precipitation. ion exchange chromatography oil DEAE-cellulose, CM-cellulose, and Q-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The hemagglutinating activity of the lectin could not be inhibited by simple sugars but was inhibited by the polysaccharide inulin. The activity was stable up to 70 degrees C but was acid and alkali-labile. Salts including FeCl3, AlCl3, and ZnCl2 inhibited the activity whereas MgCl2, MnCl2. and CaCl2 did not. The lectin stimulated mitogenic response Of mouse splenocytes with the maximal response achieved by 1 mu M lectin. Proliferation of tumor cells including MBL2 cells, HeLa cells, and L1210 cells was inhibited by the lectin with an IC50 of 2.5, 5, and 10 mu M, respectively. However, proliferation of HepG2 cells was not affected. The novel aspects of the isolated lectin include a novel N-terminal sequence, fair thermostability, acid stability, and alkali stability, together with potent mitogenic activity toward spleen cells and antiproliferative activity toward tumor cells. (c) 2006 Elsevier Inc. All rights reserved.