Clinical studies have suggested that IL-4 can be used as a biological marker to evaluate disease severity and activity.[58] Compared to inactive, obsolete, or cured control groups, individuals with active pulmonary TB have increased levels of IL-4.[62] Additionally, the concentration of IL-4 in positive sputum smears and culture results was higher than that in negative sputum smears and culture results.[12] These meta-analyses also suggested that the level of IL-4 in patients with active TB was higher than that in patients with latent TB. This evidence concerns the gene IL4 and pulmonary tuberculosis.