Fig. 4.

Characterization of SARS-CoV S-, M-, E- and N-antigen-specific cytokine-producing cells in PBMCs. PBMCs from SARS-recovered donors and healthy unexposed individuals were incubated with S, M, E or N peptides for 6 h. Cell-surface and intracellular cytokine staining for IFN-γ, IL-2 and TNF-α were performed. More than 300,000 cells were acquired on a FACSCalibur flow cytometer. The cells were first gated on CD4⁺ T or CD8⁺ T cells and subsequently analyzed for cytokine expression. The results shown are the percentage of cytokine-producing cells in CD4⁺ or CD8⁺ T cells from different patients after stimulation and subtracting the isotype control. Each individual point represents one result from one donor. Bars indicate mean values. *P < 0.05, NS: P > 0.05. a S peptides, b M peptides, c E peptides, d N peptides. e Multiple cytokine analysis of CD4⁺ and CD8⁺ T cells following S peptide stimulation