Mushroom immunomodulatory proteins possess potential thermal/freezing resistance, acid/alkali tolerance and dehydration stability

Mushroom lectins have been reported as immunomodulatory proteins. To evaluate their functionalities, as affected by various industrial procedures, two mushroom proteins, including Agaricus bisporus lectin (ABL) and the immunomodulatory protein of Auricularia polytricha (APP), were treated by various methods, mimicking food processing procedures, in prior-to-cell experiments, and their macrophage-activating functionalities were determined in the induction of tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO) productions by RAW264.7 cells in vitro. The remaining activities of ABL and APP, after autoclave treatment (121 °C, 15 min), were observed to be 77.4% and 80.7%, respectively, in their stimulations of TNF-α production by cells. Boiling (100 °C, 30 min) and freezing (−80 °C, 24 h) treatments did not reduce their effects on TNF-α and NO secretions, while treating with pH 2 and pH 13 buffers only resulted in insignificant decrease of the ABL- and APP-induced TNF-α and NO production. Moreover, ABL and APP also withstood vacuum dehydration with 96.5% and 84.6% of activities being retained, respectively, in their stimulations of TNF-α production. These findings revealed that ABL and APP had thermal/freezing-resistant, acid/alkali tolerance and dehydration stable properties, and that they were potential candidates, as stable immune stimulants, for health food and pharmaceutical utilization.