gammadelta T cells response to Mycobacterium tuberculosis in pulmonary tuberculosis patients using preponderant complementary determinant region 3 sequence.

摘要

BACKGROUND & OBJECTIVES: The unique immunological functions of gammadelta T lymphocytes to contribute immunity against Mycobacterium tuberculosis attracted interest of researchers. However, little is known about the specificity of gammadelta Tau cell in tuberculosis patients and the lack of exact tuberculosis antigen recognized by gammadelta T cells limited its application. The analysis of complementary determinant region (CDR)3 sequence characteristic in gammadelta T cells of tuberculosis patients would contribute to understand the distribution specificity of gammadelta T cell. In present study, we investigated the diversity of the gamma9/delta2 T cell immunorepertoire and analysed the specificity of the expressed CDR3 in pulmonary tuberculosis patients. METHODS: The total RNA in peripheral blood mononuclear cell of 50 pulmonary tuberculosis patients and 10 healthy controls was extracted. The polymerase chain reaction was used to specifically amplify the CDR3 region of gamma9 and delta2 chain. The PCR products were ligated into the pGEM-T easy vector. The plasmid DNA was sequenced using the ABI3700 and the T7 primer. RESULTS: Our findings showed that predominant CDR3 sequence of delta2 chain in pulmonary tuberculosis patients was CACDTLVSTDKLIFGKG. The sequence specifically exists in almost all pulmonary tuberculosis patients. The conserved hydrophobic acid residue in 97 positions is present in the gammadelta T cell reactive to M. tuberculosis. The length of delta2 CDR3 in pulmonary tuberculosis patients has no relation with the disease progress. INTERPRETATION & CONCLUSIONS: Our results suggest that gammadelta T cells appear to use CDR3 sequence to recognise M. tuberculosis antigen. gammadelta T cells reactive to M. tuberculosis were diverse and polyclonal.