['Activated hexose correlated compound (AHCC), derived from shiitake mushrooms, increases resistance to infection in immunocompromised hosts with positive effects on dendritic cells, natural killer cell function and interleukin 12 production. It may also be attenuating the systemic inflammatory response by regulating the secretion of cortisol and norepinephrine (NE).', 'Female Swiss-Weber mice were pretreated with AHCC (Amino Up Chemical Co., Sapporo, Japan) or water by gavage for 10 days before undergoing cecal ligation and puncture (CLP). Peritoneal exudate cells and blood samples were harvested at 4 hours and 24 hours following CLP. Plasma and peritoneal concentrations of cortisol and NE were obtained using enzyme-linked immunosorbent assay. Peritoneal bacteria were quantified by colony counts after 4 hours and 24 hours. Significance was denoted by a p < 0.05.', 'Plasma and peritoneal cortisol concentrations were increased 4 hours after CLP compared with normal controls, with no difference between the pretreated groups. Concentrations of cortisol decreased from 4 hours to 24 hours after CLP with AHCC (plasma, p = 0.009; peritoneal, p < 0.001), and peritoneal cortisol at 24 hours was lower with AHCC as compared with water (p = 0.028). There was no change in plasma or peritoneal NE concentrations at 4 hours. At 24 hours, higher concentrations of NE were detected in both plasma and peritoneal fluid, with lower plasma concentrations in those gavaged with AHCC (p = 0.015). There was no significant difference in peritoneal bacteria counts.'] Does a natural immune modulator attenuate stress hormone and catecholamine concentrations in polymicrobial peritonitis?