Figure 3.

Antigen-specific cytokine-producing populations at day 18. The frequency of CD4⁺ and CD8⁺ live-attenuated Salmonella Typhi strain Ty21a (Ty21a)-responsive and heterologous influenza virus–responsive populations expressing any combination of interferon γ, tumor necrosis factor α, and/or interleukin 2 above background. Staphylococcal enterotoxin B (SEB)–stimulated control data is also included. For control (C; closed squares, circles, and triangles) and vaccinated (V; open squares, circles, and triangles) volunteers, measurements were made at the duodenal mucosa (A), the colonic mucosa (B), and in peripheral blood (C). Horizontal bars represent mean values (comparisons were made using unpaired t tests). Abbreviation: NS, not significant.