The peritoneal fluids from TB patients contained approximately 6 times more non-stimulated IFN-γ-producing CD4+ T lymphocytes than to those of non-TB patients (medians 0.630% and 0.105%, Fig 1, upper and lower panels, TB and non-TB respectively), whereas the proportion of IFN-γ-containing CD8+ T lymphocytes was similar in the two groups of patients (medians 0.09% and 0.08% for TB and non-TB). This evidence concerns the gene IFNG and tuberculosis.