Effect of AHCC on the immune response to primary influenza infection in young and aged mice

Abstract

The emergence of H5N1 avian influenza and the threat of new or adapted viruses in bioterrorism have created an urgent interest in identifying agents to enhance the immune response to primary virus infection. Influenza (FLU) virus is a public health concern, particularly among the elderly, and is well-studied in relation to changes that occur with age. Aged mice exhibit reduced antibody titers, impaired CTL responses, and increased virus burden after primary infection with FLU. Our data indicate that natural killer (NK) cell activity is also reduced by 50% in both the spleen and lungs of aged mice, while the number and percent of total lymphocytes do not differ with age in response to infection. Active hexose correlated compound (AHCC) is an agent reported to increase NK cell activity, survival, and bacterial clearance in young mice stressed by head-down tilt, although no data currently exist on the effects of AHCC on the response to FLU infection. C57Bl/6 mice were supplemented with 1g AHCC/kg body weight/day for 1 week prior to and throughout infection with influenza A (H1N1, PR8). Spleen and lung lymphocytes were assessed for NK cytotoxicity by 51Cr release assay and phenotype by flow cytometry, and lung viral clearance by MDCK infectivity. AHCC appears to increase NK activity in the spleen and enhance NK cell recruitment to the lung by 48 hours following FLU infection. Bolstering innate immunity with dietary bioactives may be one avenue for improving the immune response to primary FLU infection. Supported by Amino Up Chemical Company