FIG. 2.

Comparison of basal (no-antigen control) and PPD-RT23-induced IFN-γ, IL-4, and IL-10 expression in pulmonary tuberculosis patients (n = 43) and controls from areas of endemicity (n = 44) from south India, studied by the whole-blood culture method. Fifty microliters of whole blood diluted to 200 μl with RPMI medium was incubated for 48 h in the presence or absence of antigen in a CO₂ incubator. Ninety-one percent of the controls and 71% of the patients expressed IFN-γ in the no-antigen control mixture, while all of the patients and controls expressed IFN-γ in the presence of PPD. In contrast, only certain individuals (responders, positives), produced IL-4 and/or IL-10 in either the presence or absence of PPD. The values of cytokine expression (percentage of β-actin expression) of a sample in the absence and presence of PPD are connected by lines, and the paired t test (PT) or WRT was applied to determine the significance.