CD4 and tuberculosis: Since there were no significant differences in IFN-γ and IL-17 levels or IFN-γ and IL-17 producing CD4+ T cells between cavitary and non-cavitary PTB, we looked through all clinical characteristics of the subjects, then further subdivided the patients according to the diameter and number of cavities in cavitary PTB group and the field range of TB lesions on the chest CT in all patients.