In tuberculous pleuritis in humans, localized rather than systemic action of the cell-mediated immune response, associated with higher proportions of IFN-γ secreting lymphocytes in the pleural cavity as compared to the blood, has been demonstrated by several research groups [34, 35] and is suggested to be responsible for mycobacterial clearance without therapeutic intervention [36]. The gene discussed is IFNG; the disease is pleural tuberculosis.