Objective: To study the clonal characteristics of peripheral T cells and anti-tumor immunology in the patients with colorectal cancer by analyzing T cell receptor beta (TCRbeta) gene repertoire and complementarity determining regions 3 (CDR3) amino acid sequence of the peripheral blood cells (PBL).
Methods: The 24 TCRbetaV genes from PBL in pre-operation and post-operation and colorectal cancer tissues, were amplified by the method of combined reverse transcriptase-polymerase chain reaction (RT-PCR) with denaturation polyacrylamide sequencing gel electrophoresis, which is called TCRbeta gene repertoire. In order to analyze the clonality of the over-expressing bands and the CDR3 sequence, the PCR production was sequenced directly.
Results: TCRbeta gene repertoire of PBL in the tumor-bearing patients was clonally expressed, which indicated that there were monoclonal or oligoclonal expansion of T lymphocytes. Some of the clonal T cells in PBL had the same CDR3 amino acid sequence motifs with the clonal T cells in the tumor infiltrating lymphocyte(TIL). The patients with clonal expansion of T cells in PBL had lymph node metastases, but there was no recurrence within 10 months after operation.
Conclusion: There is oligoclonal proliferation of T cells in the blood of tumor-bearing patients. It is possible that the clonal T lymphocytes are the tumor associated antigen specific anti-tumor T lymphocytes.