IL4 and tuberculosis: To address this problem, we looked at levels of the prototypical Th1/Th2 cytokines IFN-γ and IL-4, and the IL-4 antagonist, IL-4δ2 in TB patients and their close, household contacts, both at entry to the study (when the index case was first identified) and at the conclusion of treatment of the index case (6–8 months later).