Human peripheral blood γδ T cells are uniformly sensitive to destruction by the lysosomotropic agents leucine methyl ester and leucyl leucine methyl ester

Treatment of peripheral blood mononuclear cells (PBMC) with the lysosomotropic agent leucine methyl ester (Leu‐OMe) eliminates monocytes/macrophages and cytotoxic lymphocytes including CD3− CD16+ natural killer (NK) cells and a fraction of T cell receptor (TcR)αβ+ CD8+ T cells. We report that freshly isolated peripheral blood γδ T cells are highly sensitive to Leu‐OMe treatment as well. After incubation of PBMC with 5 mM Leu‐OMe or incubation of purified T cells with 50 μ.M leucyl leucine methyl ester (Leu‐Leu‐OMe) and subsequent overnight culture, CD3−CD16+ NK cells and γδ T cells were no longer detectable by immunofluorescence analysis. The two major γδ T cell subsets Vγ9+Vδ2+ and Vγ9‐Vδ1+ were equally susceptible to Leu‐OMe and Leu‐Leu‐OMe treatment. The elimination of Vγ9+ T cells by Leu‐OMe treatment was confirmed in functional assays. Stimulation of peripheral blood T cells with killed mycobacteria resulted in selective expansion of Vγ9+ T cells. In contrast, no activation of γδ T cells was elicited in Leu‐OMe‐treated responder T cells stimulated with killed mycobacteria.