Human Th1 cell lines recognize the Mycobacterium tuberculosis ESAT-6 antigen and its peptides in association with frequently expressed HLA class II molecules.
We have used a synthetic-peptide approach to map epitope regions of the Mycobacterium tuberculosis ESAT-6 antigen recognized by human T cells in relation to major histocompatibility complex (MHC) restriction. ESAT-6-specific CD4+ T-cell lines were established by stimulating peripheral blood mononuclear cells from 25 HLA-DR-typed tuberculosis patients with complete antigen in vitro. The established T-cell lines were then screened for proliferation and interferon-gamma (IFN-gamma) secretion in response to eight overlapping 20-mer peptides covering the ESAT-6 sequence. The response of the T-cell lines to ESAT-6 and peptides from a human leucocyte antigen (HLA)-heterogeneous group of donors suggested the presence of multiple epitopes and promiscuous recognition of the antigen. Analysis of antigen and peptide recognition in the presence of anti-HLA class I and class II antibodies suggested that the T-cell lines recognized ESAT-6 in association with HLA-DR and -DQ molecules. Furthermore, testing of selected T-cell lines with ESAT-6 and the peptides in the presence of autologous and allogeneic HLA-DR- and -DQ-typed antigen-presenting cells identified HLA-DR2, -DR52 and -DQ2 amongst the HLA molecules involved in the presentation of ESAT-6 and its peptides to human Th1 cells. In addition, the T-cell lines were cytotoxic for monocytes and macrophages pulsed with ESAT-6 and peptides. In conclusion, the recognition of ESAT-6 by IFN-gamma-secreting and cytotoxic CD4+ T cells in association with frequently expressed HLA class II molecules supports the application of this antigen to either specific diagnosis or subunit vaccine design.
Mustafa
A S
AS
Department of Microbiology; Department of Medicine, Kuwait University, Safat; Chest Diseases Hospital, Kuwait. abusalim@hs.kuniv.edu.kw
Shaban
F A
FA
Al-Attiyah
R
R
Abal
A T
AT
El-Shamy
A M
AM
Andersen
P
P
Oftung
F
F
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018604:Epitope Mapping; D006683:HLA-DQ Antigens / Q000276:immunology*; D006684:HLA-DR Antigens / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D010455:Peptides / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D010455:Peptides; D007371:Interferon-gamma