Evaluation of Humoral Immunity to Mycobacterium tuberculosis-Specific Antigens for Correlation with Clinical Status and Effective Vaccine Development

Table 3

Serum IgA responses to seven mycobacterial antigens.

Group	ELISA index at 450 nm (mean ± SD) and positive rate (%)
	ESAT-6	CFP-10	MDP1	Ag85A	Acr	HBHA	HrpA
Cut-off values	1.496	0.567	1.115	0.577	0.738	1.015	0.901
Negative control	1.564 ± 1.533; 32.4%	1.007 ± 1.041; 58.1%	2.290 ± 2.277; 63.5%	1.354 ± 1.382; 64.9%	0.881 ± 0.739; 41.9%	1.132 ± 1.140; 35.1%	0.932 ± 0.813; 39.2%
Active disease	2.189 ± 2.192; 59.5%	1.246 ± 1.312; 78.4%	1.137 ± 0.828^a; 30.7%	1.470 ± 1.664; 85.2%	1.252 ± 1.549^b; 58.0%	1.713 ± 1.955; 55.7%	0.751 ± 0.333; 29.5%
Past disease	1.336 ± 1.128^c; 23.8%	0.976 ± 0.715; 72.6%	1.166 ± 1.232^d; 34.5%	1.037 ± 0.686; 79.8%	0.831 ± 0.495; 50.0%	1.283 ± 0.954; 50.0%	0.771 ± 0.356; 35.7%
Latent TB infection	0.783 ± 0.246^e; 0.0%	0.793 ± 0.307; 64.7%	0.879 ± 0.297^f; 11.8%	0.898 ± 0.395; 58.8%	0.606 ± 0.221; 23.5%	0.772 ± 0.299; 17.6%	0.595 ± 0.285; 17.6%
AUROC	0.63	0.53	0.66	0.57	0.59	0.62	0.53

(active versus control), ^b (active versus past), ^c (active versus past), ^d (past versus control), ^e (active versus latent), ^f (latent versus control).
Optimal cut-off values were chosen when the Youden’s index (sensitivity and specificity − 1) was maximal.
AUROC: areas under the receiver operating characteristic curve.