AIM： To investigate the effect of Auricularia Polytricha Sacc Polysaccharide（ APSP） on protein kinase A（ PKA） activity in murine peritoneal macrophages METHODS： New ion－ pair RP－ HPLC method was used to determinate the activity of PKA in murine peritoneal macrophages RESULTS： APSP（ 80mg/L） induced activation of PKA in murine peritoneal macrop_ hages； the peak appeared at 8 minutes and the activity of PKA returned to the basic level at 20 minutes CONCLUSION： The immunopoteniating effect of APSP may be associated with its activating effect on PKA in murine peritoneal macrophages