Fig. 3.

In contrast to αβ T lymphocytes or CD3-negative cells, a substantial proportion of activated Vδ2 T lymphocytes produce multiple cytokines. Human PBMCs were incubated (24 h) in culture medium with of 128 μM sodium pamidronate and the IFN-γ and TNF-α intracellular presence was assessed by flow cytometry. During the last 4 h of incubation, brefeldin A (10 μg/ml) was present to block the cytokine release from cells. Polyclonal stimulation with concanavalin A (not shown) generated a very similar pattern—that is large numbers of Vδ2+ CD3+ double producers (in contrast to predominant single producers in the αβ + CD3+ and Vδ2- CD3-pools) with the exception of substantially larger amounts of single-TNF-α-positive αβ T cells. The cytokine production by the αβ+ CD3+ or Vδ2- CD3-cells in pamidronate-stimulated cultures was inhibited by anti-IFN-γ mAbs suggesting that IFN-γ released by pamidronate-stimulated Vγ9Vδ2 T cells may be an important factor in the induction of cytokine synthesis by the tested non-Vγ9Vδ2 T cell pools.