An agglutinin with mitogenic and antiproliferative activities from the mushroom Flammulina velutipes.

A hemagglutinin with a molecular mass of 12 kDa was isolated from the fruiting bodies of the mushroom Flammulina velutipes. Its molecular mass is similar to that of the fungal immunomodulatory protein isolated from F. velutipes (FIP-fve) with ice-cold 5% acetic acid and 50 mM 2-mercaptoethanol as extraction medium and to that of the larger 12 kDa subunit of F. velutipes lectin isolated with phosphate buffer as extraction medium. Its hemagglutinating activity cannot be inhibited by a variety of carbohydrates tested. The activity is stable between pH 4 and pH 11. Loss in activity occurred when the temperature is raised to 60 C and 70 C. Activity is indiscernible at and above 80 C. Its N-terminal sequence shows differences from that of FIP-fve. F. velutipes hemagglutinin stimulates [3H-methyl] thymidine uptake by mouse splenocytes. It inhibits proliferation of leukemia L1210 cells with an IC50 of 13 microM.