CD4 and tuberculosis: The percentages of Foxp3+CD4+ T cells secreting TGF-β were significantly higher in both TB group and HIV group than in HC group (p=0.029; p=0.026), and the HT group had a higher percentage of Foxp3+CD4+ T cells secreting TGF-β than the TB group (p=0.038), suggesting that HIV/TB co-infection may enhance the ability of CD4+ Treg cells to secrete TGF-β.