Figure 5. Sialidase treatment of murine sDCs induces OVA-specific CD4⁺ and CD8⁺ T cell proliferation and activation.

Murine sDCs were pulsed with OVA for 4h and treated or not with sialidase for 1h. A. Desialylated sDCs strongly induce proliferation, activation and differentiation of CD4 + T cells into a Th1 effector phenotype. Splenocytes from OT-II mice were isolated and co-cultured with sDCs for 72h in a ratio of 1:2 (DCs:splenocytes). After 72 h, the percentage of proliferating and activated CD4⁺ T cells was determined by flow cytometry using the CFSE dilution assay and evaluating the expression of CD69 and CD44, respectively (gating on CD4⁺ T cells). B. Desialylated sDCs induce activation of CD8 + T cells. Splenocytes from OT-I mice were isolated and co-cultured with sDCs for 72h in a ratio of 1:2 (sDCs:splenocytes) The proliferation of CD8⁺ T cells was determined by CFSE dilution and the activation determined based on the expression of CD69 and CD44 (gating on CD8⁺ T cell). The secretion of IFN-γ, IL-6, and TNF-α into the supernatants of co-cultures was evaluated by ELISA. Graph values represent the percentage of CFSE^low cells, percentage of CD69⁺CD44^high cells and cytokine concentration (pg/mL) (average ± SEM) from 3 independent assays. Statistical significance (*P < 0.05 or **P < 0.001), calculated using t-test, refers to the difference between fully sialylated and desialylated sDCs.