Extended Data Fig. 2: In vivo testing of antigen-reactive T cells.

NSG mice were immuno-reconstituted with human PBMC (10 million/mouse) and immunized with SARS-CoV-2 protein (10 μg/mouse). In addition, mice received CFSE-labeled autologous Mϕ loaded with SARS-CoV-2 protein. After 7 days, the spleen was harvested and activation markers on human CD3⁺ CD4⁺ T cells were analyzed by flow cytometry. a. Schematic graph for the in vivo model. b. Flow cytometric detection of CFSE⁺ CD163⁺ human macrophages in the spleen. c. Gating strategy for human T cells in the spleen. Cells in CD3⁺CD4⁺ gate were correspond with Figs. 1j,2n and 6j.