Middle-aged Subjects With Habitual Low-speed Cycling Exercise Have Greater Mononuclear Cell Responsiveness Against Human Hepatitis B Virus Surface Antigen

SummaryBackgroundWhether middle-aged people with habitual cycling exercise (HCE) at low intensity in the morning have higher immunity against hepatitis B virus than sedentary controls (SCs) is a health issue in the elderly.MethodsConditioned media (CM) were prepared by stimulating isolated human peripheral blood mononuclear cells (MNC) with phytohemagglutinin (PHA) or assessment of their inhibitory effects on hepatitis B surface antigen expression in human hepatoma Hep3B cells.ResultsWith the percent of maximal oxygen uptake at about 45.52% and percent of maximal heart rate at about 68.58% during a cycling exercise program in the present study, we considered HCE as an aerobic and a low to moderate exercise for the elderly. The concentrations of secreted cytokines such as interferon gamma, tumor necrosis factor a and interferon alpha were higher in the MNC-CM from the HCE group than from the SC group. The inhibitory rates of MNC-CM of the HCE group against hepatitis B surface antigen expression were higher than that of the SC group. In the same stimulating concentration of PHA (10 μg/mL), the relative hepatitis B surface antigen expression in MNC-CM of the HCE group was 64.7% versus 81.5% of the SC group. The reduction in inhibitory rates in cytokine neutralization experiments suggests crucial roles of these cytokines for the inhibitory effect of HCE-PHA-MNC-CM against hepatitis B surface antigen expression.ConclusionThe results reveal that the immune response of MNC, which are stimulated by PHA to suppress hepatitis B surface antigen expression, is greater in middle-aged subjects with low-speed HCE than in sedentary subjects.