eGFP, luciferase, and DTx receptor are functionally expressed by γδ T cells. (A) Two-photon in vivo imaging of Tcrd-GDL mouse ear skin and small intestine. Green, γδ T cell eGFP; blue, second harmonics (ear skin) or Hoechst 33342 nuclear staining (small intestine). Bars: 50 µm (ear skin); 15 µm (small intestine; see also Videos 1 and 2). (B) eGFP expression by peripheral lymph node γδ T cells (green, gated as CD45⁺Tcrβ^–CD3⁺TCRγδ⁺), αβ T cells (blue, gated as CD45⁺Tcrβ⁺CD3⁺), and B cells (red, gated as CD45⁺Tcrβ^–CD3^–CD19⁺) of a Tcrd-GDL mouse and CD45⁺ cells of a C57BL/6-NCrl mouse (WT, filled gray line). Shown is one representative histogram of two experiments with each n = 2–3 mice per group. (C) Bioluminescence by functional luciferase expression was detected by IVIS in at least two independent experiments with n = 1–2 mice each. C57BL/6-NCrl WT and Tcrd-GDL were sacrificed 10 min after injection of d-luciferin and the indicated organs were displayed for imaging. Color bar corresponds to signal intensities measured as photons. c, colon; k, kidney; li, liver; lu, lung; pl: peripheral lymph node; si, small intestine; sp, spleen; st, stomach; t, thymus. (D) Depletion of γδ T cells using DTx was analyzed by flow cytometry. Representative contour plot of pLN T cells (CD3⁺ cells) of Tcrd-GDL mice treated with PBS (ctrl.) or DTx (top). Cell counts of indicated cell populations in pLNs of DTx- (white bars) and PBS- (black bars) injected Tcrd-GDL and C57BL/6-NCrl WT mice (bottom). Bar graphs show pooled data from four independent experiments with each n = 1–3 mice per group, Kruskal Wallis test with Dunn's Multiple Comparison post-tests. *, P < 0.05; ns, not significant.