In conclusion, the correlation between ESAT-6 SFC counts and cavitation on baseline chest radiograph, the decline in SFC counts during treatment, and the observed differences in SFC counts between the group having positive 8-week cultures versus the group having negative 8-week cultures indicate that IFN-γ-producing RD1-specific T cells, as measured by the T-SPOT.TB assay, may be directly related to bacterial load in individuals undergoing treatment for pulmonary TB. This evidence concerns the gene IFNG and tuberculosis.