[Proliferation of specific cytotoxic T lymphocytes induced by immunoglobulin heavy chain framework region-derived antigenic nonapeptides].

OBJECTIVE

To identify that immunoglobulin heavy chain framework regions-derived peptides function as cytotoxic T lymphocytes epitopes.

METHODS

Seven IgHV gene families were respectively amplified by PCR and directly sequenced for 108 acute lymphoblastic leukemia cases. Sequences available were translated into amino acid sequences. Bioinformatics were applied for analyzing recombination patterns and gene mutations of the IgHV genes. Softwares SYFPEITHI and BIMAS were used for predicting the T cell epitopes in the immunoglobulin heavy chain variable regions. To determine whether the predicted peptides have immunogenicity, a IgHV1 family nonapeptide QLVQSGAEV was synthesized as a representation and T2 binding assay of this peptide was performed, inducing proliferation of T cells from normal HLA-A * 0201 peripheral blood lymphocytes (PBLs) with QLVQSGAEV-loaded antigen presenting cells, and detecting the proliferating T cells by HLA-A * 0201/QLVQSGAEV tetramers.

RESULTS

Complete IgHV gene rearrangements were identified in 66% cases. Among 40 B-ALL IgHV sequences available, 26 were predicted for antigenic nonapeptides that are likely to bind to HLA-A * 0201 molecule. Twelve peptides were acquired. Except one peptide derived from CDR3, 10 (83%) peptides were located in the immunoglobulin heavy chain framework regions. Moreover B-ALL belonging to the same IgHV family shared 1 - 2 peptides. Synthesized peptide QLVQSGAEV up-regulated HLA-A * 0201 expression 1.63 times on T2 cell surface. PBLs from a normal HLA-A * 0201 donor were stimulated with QLVQSGAEV-loaded autologous PBMCs and T2, the CD8(+) tetramer(+) cells in gated lymphocyte population increased from 1.64% after the first stimulation to 82.57% after the third stimulation.

CONCLUSION

Immunoglobulin heavy chain framework region genes encode IgHV family-specific peptides recognized by CTLs. Specific CTLs remain in human peripheral T cell repertoire. Immunoglobulin heavy chain framework-derived peptides function as T cell epitopes to induce the proliferation of specific CTLs.