TABLE 3.

IFN-γ or PBMC proliferation induced in response to PPD^a

Subject condition	Mean assay result ± SEM (no. of subjects)
	Q-TB (IU/ml)	Diluted whole blood (IU/ml)	Whole-blood intracellular staining (% positive cells)	PBMC-cytokine (IU/ml)	PBMC-proliferation (SI)
Active tuberculosis	40.2 ± 11.5b (20)	71.4 ± 16.4c (20)	1.3 ± 0.4d,f (20)	56.6 ± 22.0e (17)	164.3 ± 50.5 (17)
BCG unvaccinated	6.4 ± 2.6 (19)	3.1 ± 1.2 (19)	0.07 ± 0.02 (18)	8.8 ± 7.4g (17)	91.3 ± 25.8 (18)
BCG vaccinated	17.9 ± 11.9 (4)	33.7 ± 22.8 (3)	0.2 ± 0.1 (5)	54.7 ± 30.6 (2)	200.1 ± 61.5 (4)

^aIFN-γ was measured by ELISA and is expressed in IU/ml or was measured by intracellular staining and is expressed as the percentage of positive cells. PBMC proliferation was measured by [³H]thymidine incorporation and is expressed as the SI. The differences between the active tuberculosis patients, unvaccinated individuals, and vaccinated individuals were assessed by the Mann-Whitney U Test.

^bP < 0.001 compared with the results for the BCG-unvaccinated controls.

^cP < 0.001 compared with the results for the BCG-unvaccinated controls.

^dP < 0.001 compared with the results for the BCG-unvaccinated controls.

^eP = 0.001 compared with the results for the BCG-unvaccinated controls.

^fP = 0.008 compared with the results for the BCG-vaccinated controls.

^gP = 0.046 compared with the results for the BCG-vaccinated controls.