Objective: To determine CD4(+) CD25(+) T regulatory cells (Tregs), forkhead box P3 (FoxP3) mRNA expression and levels of cytokines secreted by peripheral blood mononuclear cells (PBMCs) in individuals responsive or unresponsive to hepatitis B (HB) vaccination, and to explore the relationships between immune response and immune regulatory cells or cytokines.
Methods: Based on the antibody against hepatitis B surface antigen (HBsAg) after HB vaccination, the CD4(+) CD25(+) Tregs frequencies in PBMCs from 18 responders, 22 nonresponders and 10 non-immunized healthy controls were analyzed by flow cytometry. The expression of FoxP3 mRNA in PBMCs with or without stimulation of phytohemagglutinin (PHA)and HBsAg was analyzed by real-time quantitative PCR. Levels of IL-4, IL-12, IL-18, and IFN-γ secreted by PBMCs after PHA and HBsAg stimulation were analyzed by enzyme-linked immunosorbent assay.
Results: The ratio of CD4(+) CD25(+) Tregs to CD4(+) T cells in the nonresponders was markedly higher than that in the responders (P<0.05), but lower than that in the controls (P<0.01). FoxP3 was differentially expressed among the responders, nonresponders, and controls in PBMCs before and after PHA and HBsAg stimulation, and nonresponders had the highest FoxP3 mRNA expression (P<0.05 or P<0.01). The content of IFN-γ by PBMCs after PHA and HBsAg stimulation was markedly lower in the nonresponders as compared with the controls and responders (P<0.05). However, there were no significant differences in the levels of IL-18, IL-4, and IL-12 from PBMCs after PHA and HBsAg stimulation between the responders and controls as well as the nonresponders (P>0.05).
Conclusion: CD4(+) CD25(+) FoxP3(+) Tregs may be involved in the negative regulation of responses to hepatitis B vaccination. Immunologic non-responses to hepatitis B vaccination may be related to IFN-γ hyposecretion in PBMCs.