RESUMO
OBJECTIVE: To evaluate the 65 kD heat shock protein (hsp) antigen in serum samples of tuberculosis (TB) patients by enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies (mAbs) specific to the 65 kD hsp antigen for the diagnosis of TB. DESIGN: Serum samples were obtained from 188 different groups of patients (confirmed TB [n = 24], clinically suspected TB [n = 48], non-TB disease controls [n = 74] and healthy individuals [n = 42]) and analysed by ELISA using mAbs to the 65 kD hsp antigen. The Kruskal Wallis test (non-parametric analysis of variance) with the Dunnett post test was used for statistical analysis. RESULTS: The method yielded 82% sensitivity and 89% specificity for the diagnosis of TB. The mean (+ or -SD) absorbance value of the 65 kD hsp antigen in TB patients (1.73 + or - 0.27) was significantly higher than in the non-TB disease control group (1.12 + or - 0.42, P < 0.001) and was also higher than among healthy individuals (1.06 + or - 0.42, P < 0.001). CONCLUSION: The detection of the 65 kD hsp antigen in serum samples from confirmed and suspected TB patients by ELISA using mAb against purified 65 kD antigen gives a reliable diagnosis and could be considered as a diagnostic marker for TB. The absence of the 65 kD hsp antigen in healthy control BCG-vaccinated subjects indicates the diagnostic value of this assay in regions of endemicity.
