In Gambian TB patients, T cell response to PPD from blood or pleural fluid was impaired pre-treatment, that changed to IFN-γ release after successful treatment or IL-4 after treatment failure; addition of IFN-α or IL-12 in vitro pre-treatment could alter the response to Th1 suggesting that immunotherapy could increase host defense against mycobacteria [28]. This evidence concerns the gene IL4 and tuberculosis.