HIV-1 Tat exhibits clade-specific cytokine induction in monocytes. We investigated if Tat clades A-D can alter tumour necrosis factor (TNF)-α and interferon (IFN)-γ production by total and Vγ9Vδ2 T cells in vitro. Tat clade B, but not C, augmented TNF-α production by THP-1 cells. However, Tat clades A-D did not affect TNF-α or IFN-γ production or secretion by resting or activated conventional and Vγ9Vδ2 T cells. Therefore, transactivation of cytokines by Tat is immune cell-specific.