The comparison of different antigens in enzyme-linked immunospot assay for the diagnosis of tuberculosis.]

To compare different Mycobacterium tuberculosis antigens in enzyme-linked immunospot assay (ELISPOT) for the auxiliary diagnosis of active tuberculosis.The peripheral blood mononuclear cells (PBMC) from patients with tuberculosis and controls were co-cultured with the following antigens: purified protein derivative (PPD), early secretory antigenic target-6 (ESAT-6) and early secretory antigenic target-6/culture filtrate protein-10 fusion protein (ESAT-6/CFP-10). Spot forming cells (SFC) were enumerated by ELISPOT.PPD-ELISPOT, E/C-ELISPOT and ESAT-6-ELISPOT showed significantly higher SFC counts in active tuberculosis [255(93-526), 148(40-354) and 28(10-116) respectively] as compared to the controls [10(5-41), 10(0-20) and 5(0-15) respectively], u values were 1479.5, 1390.5 and 2510.5 respectively, all P < 0.01. Compared with the sensitivity of ESAT-6-ELISPOT (62.1%), that of E/C-ELISPOT and PPD-ELISPOT was higher (90.3% and 84.8%), chi(2) = 17.496 and 28.541, all P < 0.01. Compared with the specificity of PPD-ELISPOT (68.9%), that of E/C-ELISPOT and ESAT-6-ELISPOT was also higher (84.4% and 88.9%), chi(2) = 6.807 and 10.808, P < 0.05 and P < 0.01 respectively.E/C-ELISPOT is a promising approach to the auxiliary diagnosis of tuberculosis, but its specificity could be affected by latent tuberculosis infection.