Human T cell responses to the ESAT-6 antigen from Mycobacterium tuberculosis

Human T cell responses to ESAT-6 and eight synthetic overlapping peptides w ere investigated in tuberculosis (TB) patients and control subjects from re gions of high and low endemicity for TB, ESAT-6 was recognized by 65% of al l tuberculin purified protein derivative-responsive TB patients, whereas on ly 2 of 29 bacille Calmette-Guerin-vaccinated Danish healthy donors recogni zed this molecule, In Ethiopia, a high frequency (58%) of healthy contacts of TB patients recognized ESAT-6, All of the peptides were recognized by so me donors, indicating that the molecule holds multiple epitopes, Danish and Ethiopian patients differed in the fine specificity of their peptide respo nses. Recognition of the C-terminal region (aa 72-95) was predominant in Da nish patients, whereas recognition of aa 42-75 was predominant in Ethiopia, The relationship of these differences to the distribution of HLA types in the two populations is discussed. This study demonstrates that ESAT-6 is fr equently recognized during early infection and holds potential as a compone nt of a future TB-specific diagnostic reagent.