Mice (n = 3) were injected with (A and B) saline or (C–E) 1 × 10⁵ pfu DENV. FP tissue collected 24 hours after infection was sectioned and stained for blood vessels (CD31, blue) and the γδ TCR (green) and then probed for MC-heparin (MC granules, red). Representative control confocal images in which MCs can be viewed near blood vessels (A) without nearby γδ T cells or (B) in which γδ T cells appeared infrequently in the same field as MCs. The area in the gray box is enlarged as an inset in B, and white a arrowhead indicates γδ T cells. (C) In DENV-infected tissues, several γδ T cells clustered around MCs that appeared activated because of MC granules that were extracellular in the tissue (indicated by white arrowheads in the enlarged inset on the right). (D) Many γδ T cells formed close contacts with MCs in DENV-infected tissues. Quantification of MC–γδ T cell contacts and additional representative images are provided in Supplemental Figure 13. (E) MCs and γδ T cells were observed interacting in the peritoneal cavity 24 hours after i.p. infection with DENV (1 × 10⁶ pfu). Peritoneal lavage cells were cytospun onto glass slides prior to staining with antibodies against CD3, γδ TCR, and tubulin and probing against MC-heparin. MCs and γδ T cells appeared to form stable contacts that were visualized after isolation. Strong polarization of CD3 and γδ TCR toward the MC contact site revealed immune synapse formation. (F) No stable contacts between MCs and γδ T cells were observed in cytospins from similarly prepared uninfected peritoneal cells. Additional representative images of MC–γδ T cell conjugates in cytospins from DENV-infected mice and of control cytospins are provided in Supplemental Figure 14. Scale bars: 20 μm; 20 μm (enlarged insets in B–F).