Fig. 6

The OVA@DDAB/PLGA Nv induced the formation of germinal centers in draining LNs and proliferative response of splenocytes from immunized mice. a The number of germinal center (GL-7^hi B220⁺ cells) in draining LNs. b The follicular helper CD4⁺ T cells (Tfh, CXCR5^hi PD-1^hi CD4⁺ T cells) in draining LNs. c Germinal centers in draining LNs determined by immunohistochemical staining; The circular brown signal is the germinal center B cell, and the dense circular positive area is the germinal center, which is circular or oval with a diameter of about 0.1 to 1.0 mm, and the bright area can be identified from the outside to the inside, bar = 1.0 mm. d OD450 nm value for immunized mice splenocytes stimulated with OVA in vitro were measured by CCK-8 kit; e Proliferation index of splenocytes. Data were expressed as means ± SEM (n = 6). (**p < 0.01; ***p < 0.001; ****p < 0.0001)