Molecular features of the complementarity determining region 3 motif of the T cell population and subsets in the blood of patients with chronic severe hepatitis B

BACKGROUND: T cell receptor (TCR) reflects the status and function of T cells. We previously developed a gene melting spectral pattern (GMSP) assay, which rapidly detects clonal expansion of the T cell receptor β variable gene (TCRBV) in patients with HBV by using quantitative real-time reverse transcription PCR (qRT-PCR) with DNA melting curve analysis. However, the molecular profiles of TCRBV in peripheral blood mononuclear cells (PBMCs) and CD8(+), CD8(- )cell subsets from chronic severe hepatitis B (CSHB) patients have not been well described. METHODS: Human PBMCs were separated and sorted into CD8(+ )and CD8(- )cell subsets using density gradient centrifugation and magnetic activated cell sorting (MACS). The molecular features of the TCRBV CDR3 motif were determined using GMSP analysis; the TCRBV families were cloned and sequenced when the GMSP profile showed a single-peak, indicative of a monoclonal population. RESULTS: The number of skewed TCRBV in the CD8(+ )cell subset was significantly higher than that of the CD8(- )cell subset as assessed by GMSP analysis. The TCRBV11 and BV7 were expressed more frequently than other members of TCRBV family in PBMCs and CD8(+), CD8(- )subsets. Also the relatively conserved amino acid motifs were detected in the TCRBV22, BV18 and BV11 CDR3 in PBMCs among patients with CSHB. CONCLUSIONS: The molecular features of the TCRBV CDR3 were markedly different among PBMCs and CD8(+), CD8(- )cell subsets derived from CSHB patients. Analysis of the TCRBV expression in the CD8(+ )subset was more accurate in assessing the status and function of circulating T cells. The expression of TCRBV11, BV7 and the relatively conserved CDR3 amino acid motifs could also help to predict and treat patients with CSHB.