3× 10 min. washes in PBST (0.3% Triton X-100) and a 1 hour block in PBST/BSA (2% BSA). ATOs were stained with anti-GFP
(clone FM264G; Biolegend, San Diego, CA) at a 1:100 dilution and anti-CD3 (clone UCHT1; Biolegend, San Diego, CA) at a 1:50
dilution overnight at 4ºC. Secondary antibodies AlexaFluor-594-conjugated anti-mouse IgG (H+L) (Jackson ImmunoResearch,
West Grove, PA) and AlexaFluor-488-conjugated anti-rat IgG (H+L) (Jackson ImmunoResearch West Grove, PA) were added at a 1:200
dilution for 2 hours at room temperature. Each ATO was mounted individually in Vectashield Antifade Mounting Medium (Vector
Laboratories, England) on a concavity microscope slide (ThermoFisher Scientific, Grand Island, NY). Immunofluorescence images
were acquired on a Zeiss LSM 880 confocal microscope equipped with Airyscan and Zen software (Zeiss, Jena, Germany).