Figure 2.

Measurement of antigen-specific CD4⁺ T cell proliferation by flow cytometry. Carboxyfluorescein succinimidyl ester (CFSE)-labeled CD4⁺ T cells were injected intravenously in naïve BALB/c mice. After 24 h, virosomes (VIRO), liposomes (LIPO), or PBS was given intranasally. Then 72 h later, lung-draining lymph nodes (LDLNs) (A) and non-draining lymph nodes (NDLNs) (B) were collected and stained for surface markers. Antigen-specific T cell proliferation (CFSE dilution) was measured by flow cytometry. Panels show the expansion index (EI) of CD4⁺ T cells of six independent experiments. Note the altered Y-axis range. Statistical significance was determined by ANOVA followed by Tukey’s honest significant difference post hoc test to investigate individual paired comparisons (**p < 0.01). (C) FACS gating strategy for T cell proliferation. Cell gating includes forward and sideward scatter for live cells followed by a CD4⁺ DO11.10⁺ gating. Double positive cells were analyzed for CFSE profiles in NDLN and LDLNs to calculate the EI.