TABLE 3.

IFN-γ responses to SEB, PPDb, and PPDj in whole-blood cultures of fresh (8-h-old) or day-old samplesa

Stimulus concn (μg/ml)IFN-γ response of cow:
10311053107510891101110411121122
SEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDjSEBPPDbPPDj
Day 1
    13.163.112.251.182.871.893.171.75
    2.50.130.64b0.160.81b0.010.020.080.050.781.58b0.020.44b1.071.65b0.020.25b
    50.210.46b0.170.64b0.020.050.020.050.381.77b0.040.27b1.222.10b0.040.31b
    100.301.58b0.240.74b0.010.16b0.020.11b0.482.05b0.050.38b1.432.81b0.060.38b
    200.341.85b0.220.87b0.040.13b−0.020.10b0.592.22b0.070.44b1.532.96b0.080.40b
    400.202.07b0.160.96b0.050.16b−0.030.14b0.542.25b0.080.53b1.513.07b0.090.47b
Day 2
    13.020.921.690.771.231.070.88
    2.50.020.62b0.000.28b0.00−0.01−0.040.040.010.090.130.24b0.010.03
    50.020.52b0.020.09−0.020.000.01−0.070.010.060.200.46b0.010.06
    100.060.59b0.060.14b−0.010.010.010.010.020.080.260.69b0.010.08
    200.070.63b0.050.19b−0.010.03−0.060.060.020.090.280.82b0.020.09
    400.060.70b0.060.15b−0.010.03−0.18−0.180.040.10b0.300.90b0.040.11b
  • a All results are expressed as the OD of stimulation − no-antigen (PBS) stimulation. Three additional animals produced IFN-γ levels with PPD-PBS of <0.1 in all stimulations (positive control [SEB] >1.5) and were omitted from the table.

  • b Positive test result for paraTB by the IDEXX criterion: PPDj-PBS >0.100 and PPDb-PPDj < 0.71.