Human peripheral γδ T cells possess regulatory potential

Summary Deficiency in cd T cells aggravates colitis in animal models suggesting that cd T cells have regulatory properties. Therefore, proliferation, suppression and cytokine secretion of human cd T cells were determined in vitro. Human peripheral cd T cells were isolated from the whole blood of healthy donors by magnetic antibody cell sorting technology. The proliferation after CD3/CD28 stimulation was measured by 3 [H]thymidine incorporation. Interferon-c (IFN-c), interleukin-2 (IL-2), transforming growth factor-b (TGF-b) and IL-10 concentrations were measured by enzymelinked immunosorbent assay; TGF-b messenger RNA was also measured by reverse transcription‐polymerase chain reaction. The expression of latency associated peptide (LAP), a TGF-b complex component, intracellular cytokine content and T helper cell proliferation were measured by flow cytometry. Human cd T cells showed poor proliferation upon CD3/ CD28 stimulation and suppressed T helper cell growth stronger than CD4 + CD25 + T cells, although cd T cells were FOXP3 negative. They secreted little IL-2 but high concentrations of IFN-c, IL-10 and TGF-b. When looking at LAP expression the Vd1 subset was found to be the main TGF-b producer compared to Vd2 T cells. Taken together, peripheral cd T cells have in vitro a more potent regulatory potential than CD4 + CD25 + cells regarding T helper cell suppression. This is most likely the result of strong TGF-b secretion, particularly by the Vd1 subset.