Figure 4. IL-17-producing CD4⁺ cells were the predominant responsive cell population in SrtA/CTB-immunized mice after GAS challenge.

Mice were immunized and challenged as in Fig. 3. Five days after challenge, immunized (SrtA/CTB) and PBS control mice were euthanized and NALT cell suspensions were stained with antibodies for surface markers (CD4, CD3, DX5, and γδ TCR) as needed followed by intracellular staining with PE-IL-17 and analyzed by FACS. (A) IL-17⁺ γδ TCR⁺ (γδ T) cells. (B) IL-17⁺ DX5⁺ CD3⁺ (NKT) cells. (C) IL-17⁺ DX5⁺ CD3^– (NK) cells. (D) IL-17⁺ CD3^– CD4^– DX5^– (ILC3) cells. (E) IL-17⁺ CD3⁺ CD4⁺ CD44⁺ (memory Th17) cells. Data are means ± SEM of three mice per group. ** P≤0.01.