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

Summary 

Background

Whether 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.

Methods

Conditioned 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.

Results

With 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.

Conclusion

The 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.

Key Words:  aerobic exercise , hepatitis B surface antigen , hepatitis B virus , immunomodulation

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