Objective: To analyze peripheral blood naive T cell level, its T cell receptor (TCR) Vbeta repertoire usage profile and clonality for evaluating the recent thymic output function and the expansion feature of TCR Vbeta subfamily T cells in patients with chronic myelogenous leukemia (CML).
Methods: Quantitative detection of T-cell receptor excision DNA circles (TRECs) in peripheral blood mononuclear cells (PBMNC) from 20 cases of CML was preformed by real-time PCR (TaqMan) analysis, and TRECs-number in T-cells was calculated from peripheral blood CD3-positive cell rate. The expression and clonality analysis were detected by RT-PCR and Genescan technique in PBMNC from 14 out of the 20 patients. Nine normal individuals served as controls.
Results: A dramatic reduction of TRECs value in patients with CML was detected as compared with that in normal controls. The mean value of TRECs was 0.06 +/- 0.16 copy/1000 CD3(+) cells in CML patients while 6.84 +/- 4.71 copies/1000 CD3(+) cells in normal controls (P < 0.01). The 1 - 12 Vbeta subfamilies were variably expressed in samples from 14 patients. Genescan analysis identified clonal expanded T cells of some Vbeta subfamily from 13 cases. Vbeta3, Vbeta10, Vbeta19, Vbeta21 and Vbeta22 subfamilies clonal T cells were more frequently seen.
Conclusion: There is a prominent reduction of recent thymic output naive T cells function in CML. The predominant usage and clonal expansion of TCR Vbeta subfamily T cells could be identified, indicating that CML patients have specific immune response to leukemia associated antigen, in spite of their T cell immunodeficiency.