Analysis of the T-Cell Receptor Repertoire in the Study of Immunological Abnormalities in Myelodysplastic Syndromes (MDS).

Introduction

The myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal hematopoietic stem cell disorders, while, immunological abnormalities are frequently observed in patients with MDS^[1]. Several reports ^[2,3]revealed that about 10% of MDS patients have clinical autoimmune disorders like skin vasculitis, rheumatic disease, or autoimmune hemolytic anemia. Furthermore, serological immunological abnormalities like hyper- or hypogammaglobulinemia, positivities of antinuclear antibody, positivities of direct Coombs test, or inverted CD4/8 ratios were found in 18–65% of patients with MDS. Recently immunosuppressive therapies including prednisolone, antithymocyte globulin, and cyclosporin A (CsA) are used to treat cytopenia in some patients with MDS. We reported four patients with MDS. Rearrangements of the TCR-beta genes were seen in these patients using RT-PCR and Genescan analysis (CDR 3 length analysis). Also they had skewed TCR usages using TCR repertoire analysis.

Methods

Two patients with refractory anemia(RA), two with refractory anemia with blasts(RAEB). four males from 41to 68 yearsold. Complementarity determining region 3(CDR3) of TCR Vβ with 24 variable region gene was amplified in peripheral blood mononuclear cells, which were drawn from five patients with myelodysplastic syndromes (MDS) using RT-PCR, to observe the expression of TCR Vβreceptoroire T cells, the PCR products were further analyzed by genescan to evaluating clonality of T cells (CDR 3 length analysis), and compare results with age-matched healthy donors and patients with graft versus host disease(GVHD).

Results

We found a significantly higher number of skewed Vb profiles in the MDS and GVHD patients compared with donors. In peripheral blood T cells, Only 2-11 Vb subfamily T cells could be identified in MDS patinets, clonal expansion T cells could be found in Vb1, 3,13, 14 and 21 subfamilies.

Disussion

In this study, we evaluated the total T-cell repertoire of 4 MDS patients using gendscan analysis to look for evidence of T-lymphocyte clonality. This analysis showed that all 4 patients exhibited extensive skewing of their TCR spectratypes, suggesting clonal or oligoclonal T-cell expansions. Epperson ^[10]also reported the same results. As we know, acute and chronic graft-versus-host disease(GVHD) is a major complication after allogeneic bone marrow transplantation. GVHD is mediated by T cells that are derived from the BM graft. In this study, we compared the results of GVHD patients with that of MDS patients, and found that these two groups patients show TCR Vb skew distribution and clonal expansion. These findings provide further evidence that T cell mediated immune processes are a feature of MDS.