ABSTRACT
<p><b>OBJECTIVE</b>To investigate CD4+ CD25+ regulatory T cell frequencies in the peripheral blood of poor or non-responsiveness to Hepatitis B vaccine, and try to understand the relationship between CD4+ CD25+ regulatory T cell and poor or non-responsiveness to Hepatitis B vaccine.</p><p><b>METHODS</b>Flow cytometric analysis was employed for CD4+ CD25+ regulatory T cell frequencies in the peripheral blood of 25 cases of non-responsiveness, 30 cases of poor-responsiveness, and collected 20 cases of responsiveness as control.</p><p><b>RESULTS</b>CD4+ CD25+ regulatory T cell frequencies of responsiveness was (4.32 +/- 1.21)%, poor-responsiveness was (7.01 +/- 1.06)% and non-responsiveness was (12.75 +/- 2.01)%. It was found that non and poor-responsiveness showed a high percentage of CD4+ CD25+ regulatory T cell as compared with responsiveness (t = 8.426, t = 3.289, P<0.01).</p><p><b>CONCLUSION</b>The poor and non-responsiveness should be related with the increase of CD4+ CD25+ regulatory T cell and this might be considered as an important cause of poor and non-responsiveness.</p>