TABLE 1.

Longitudinal IFN-γ, nitrite, and TNF-α responses of blood mononuclear cells to stimulation with PPDb^a

Prechallenge or day after challenge	Mean responses ± SEMb
	IFN-γ (OD)	Nitrite (ng/ml)	TNF-α (ng/ml)
Prechallenge	0 ± 0 A	−10 ± 5 A	−0.34 ± 0.09 A
34	0.84 ± 0.26 B	129 ± 41 C	0.58 ± 0.29 B
68	0.93 ± 0.22 B	101 ± 24 BC	1.28 ± 0.38 C
124	0.55 ± 0.19 B	59 ± 23 B	−0.03 ± 0.16 A

^aBlood mononuclear cells were isolated immediately prior to challenge (day 0) and at 34 days, 68 days, and 124 days after challenge and were cultured for 48 h with medium alone or with 5 μg of PPDb per ml. IFN-γ and TNF-α concentrations were quantified by ELISA, and nitrite concentrations were quantified by the Griess reaction. Data were analyzed by repeated-measure ANOVA with P values of 0.001, 0.001, and <0.0001 for IFN-γ, nitrite, and TNF-α, respectively. Values followed by different letters are significantly different (P < 0.05).

^bValues represent mean responses (± SEM, n = 20) to PPDb stimulation minus responses to medium alone.