T cell receptor rearrangement excision circles (TRECs) and CD31+ regulatory T cells for assessing recent thymic output in patients with chronic hepatitis B

Abstract

Objective To evaluate the clinical value of combined detection of T cell receptor rearrangement excision circles (TRECs) and CD31+ regulatory T (Treg) cells for accessing the recent thymic output in patients with chronic hepatitis B. Methods Four groups involving 135 subjects were set up in this study as follows: mild chronic hepatitis B (Mild CHB, n=35), moderate chronic hepatitis B (Moderate CHB, n=35), severe chronic hepatitis B (Severe CHB, n=35) and healthy control (HCs, n=30) groups. CD4+ CD25+ Treg cells in these subjects were sorted out using magnetic cell separation. The ratio of peripheral CD31+ Treg cells to Treg cells in each group was analyzed by flow cytometry. Real-time PCR was performed to detect TRECs in CD4+ CD25+ Treg cells. The percentages of CD3+ , CD4+ and CD8+ T cell subsets were also measured. Results The ratios of CD31+ Treg/Treg cells and the numbers of TRECs in peripheral blood of the Moderate CHB and Severe CHB groups were significantly lower than those of the Mild CHB and HCs groups (P 0.05). No significant difference in the percentages of CD3+ , CD4+ or CD8+ T cell subsets was observed between the four groups (P>0.05). CD31+ Treg/Treg cell ratio had a positive correlation with the number of TRECs (r=0.551, P=0.014). Conclusions Both CD31+ Treg/Treg cell ratio and the number of TRECs were reduced in the peripheral blood of patients with moderate or severe CHB. CD31+ Treg/Treg cell ratio and the number of TRECs were positively correlated and could be used as new indices to evaluate recent thymus output. Key words: Chronic hepatitis B; CD4+ CD25+ regulatory T cell; CD31+ regulatory T cell; T cell receptor rearrangement excision circles