Our observation that there was no correlation between CD4+ count recovery after HAART and level of IFN-γ production in the HIV + TB + patients, unlike to that of HIV-TB + patients where there was a strong correlation between CD4+ T cell recovery and IFN-γ production following TB treatment (Figure 5), suggests that other factors may play a role in the impaired functional recovery of Mtb specific immune responses in the HIV + TB + patients. The gene discussed is CD4; the disease is tuberculosis.