Objective: To analyze if the cytotoxic T-cell (CTLs) are peptide-special and HLA restrict, and what is the sequence characteristic of TCRbeta genes.
Methods: Using an antigen-specific T-cell expansion system in vitro, the peripheral blood mononuclear cells (PBMCs) from healthy HLA-A0201 positive donor were stimulated by PBMCs and T2 cells loading the IgHV1-QLVQSGAEV nonapeptide or IgHV3-QLVQSGAEV, B-lymphoma-related nonapeptides, as antigen presenting cells (APCs) once a week for four weeks so as to obtain peptide-specific CTLs. PBMCs from non-HLA-A * 0201 positive donors were used as controls. The immunophenotypes of the CTLs (CD3, CD4, or CD8) were identified by flow cytometry. The proportions of CD8 and peptide/tetramer double positive cells were assayed by using peptide/ HLA tetramer method, The IFN-gamma-releasing capacity of the CTLs incubated together with different target cells was assayed by ELISA. The changes of lymphocyte clones were analyzed TCR beta genes were identified by RT-PCR and spectral type method and then sequenced.
Results: After four times stimulation, the CD4/CD8 ratio of the cultured cell decreased obviously from 1.43 to 0.10 (P < 0.05), showing a proliferation of CD8(+) CTLs. The frequency of CD8 and IgHV1-QLVQSGAEV/ HLA-A * 0201 tetramer double positive CTLs was 49.83%, significantly higher than that before stimulation (0.04%). The IFN-gamma secretion detected by ELISA indicated that these CTLs were capable of recognizing the target cells in a peptide-specific and MHC-restricted way. Spectral type method showed that the TCRbeta repertoires were skewed in only a few TCR families.
Conclusion: The peptides derived from IgHV succeeds in generation of peptide-specific CTLs in vitro in a clonality manner. These CTLs are capable of recognizing the target cells in a peptide-specific and MHC-restricted way, Understanding the function of these CTLs and the molecular structures of these TCR identification-related antigen peptides help discover the interaction between the B-cell and T-cell clones.