Objective To construct and apply a cell line screening Mycobacterium tuberculosis (Mtb)-specific tetramers of CD4+α/β T cell receptor(TCR). Methods The β chains of HLA class Ⅱ (DR) were amplified from tuberculosis patients by PCR. The pMT-HLA-DRB expression vectors that carries the HLA-DR 13 chain and pMT-HLA-DRA-P expression vectors which carries the genes of HLA-DR α chain loaded with Mtb antigen were transfected into S2 cells with the method of calcium phosphate transfection. The expressed Mtb peptide/HLA-DR complexes were primarily identified by the method of cell immunohistochemistry. The cell lines expressing Mtb peptide/HLA-DR complexes were used to screen tetramers of CD4+ TCR by flow cytometry. Results S2 cell lines expressing Mtb peptide/HLA-DR complexes on the cell surface were obtained, two kinds of Mtb specific tetramers of CD4+α/β TCR were screened. Conclusion S2 cell lines expressing Mtb peptide/HLA-DR complexes on the cell surface provide the solid basis of the further research on the TCR tetramers and are helpful for exploring new diagnostic study methods about tuberculosis and developing new vaccines.

ObjectiveTo investigate the specificity of CD4+ Vα9-J27/Vβ29-D1-J2 tetramer in detecting Mycobacterium tuberculosis(MTB) infections.MethodsThe above TCR tetramer by using biotinylated monomers expressed and purified from constructed stable Drosophila Schneider 2 cell( S2 cell) lines was prepared.The PE-labled TCR tetramer was used to costain with S2 cell lines expressing MTB prptide/HLA-DR complexes on the cell membrane,and also was used to detect tetramer-bound CD14+ monocytes and macrophages in the peripheral blood mononuclear cells (PBMC) of pulmonary tuberculosis (PTB) patients and three control groups by flow cytometric analysis.And the FITC-labled tetramer was used to examine tetramer-bound CD14+ monocytes and macrophages,and MTB antigen-specific and tetramer-bound cells by in situ staining.ResultsThe TCR tetramer was well binding with S2 cell lines expressing C14/HLA-DR *1504 on the cell membrane.By flow cytometric analysis,the percentage of tetramer-bound CD14+ monocytes and macrophages in PTB patients group was higher than the other three control groups( P＜0.001 ).By in situ staining,tetramer-bound CD14+ monocytes and macrophages,and MTB antigen-specific and tetramer-bound cells were positive in PTB tissue and negative in control pneumonia tissue.ConclusionThe spcificity of TCR tetramer in monitoring MTB infections by flow cytometric analysis and in situ staining could be seen,which laid a laboratory foundation in the diagnosis and immune mechanism research of TB by using TCR tetramers.