Figure 1

IFN-γ secretion by PBMC from PPD^-, PPD⁺ and BCG-vaccinated healthy donors and from patients with active TB in the presence of rPPE44, as determined by ELISpot (panel A) and ICC (panel B). ELISpot results are expressed as spot-forming units (SFU) per 5 × 10⁴ cells; SFU values above 5, indicated by a horizontal dotted cut-off line, were considered as positive responses. ICC flow cytometry results are expressed as the % of IFN-γ⁺ CD4⁺ cells after subtracting background (% of IFN-γ⁺ CD4⁺ in the negative controls). Values above an arbitrary cut-off of 0.01% are classified as positive.