Fig. 4. Defective T_FH cells responses in Cd4-Cre:LepR^fl/fl mice after influenza virus infection.

a–e Cd4-Cre:LepR^+/+ mice (grey, n = 11) and Cd4-Cre:LepR^fl/fl mice (red, n = 8) were infected with influenza virus A/X-31 (H3N2). Mediastinal lymph nodes were analysed at day 9 post-infection. Representative FACS plots and statistics showing the CD4⁺Foxp3^-CD44^high effector cells, CD4⁺Foxp3⁺ T_REG cells (a), CD44⁺CXCR5⁺Bcl6⁺ T_FH (b), (*P = 0.0499, *P = 0.0347), IL-21 production (c), (*P = 0.0313, *P = 0.0142), B220⁺GL-7⁺Fas⁺ GC B cells (d) (*P = 0.0151, *P = 0.0249) and B220^-CD138⁺TACI⁺ ASCs (e) (*P = 0.0250, *P = 0.0409) 9 days post influenza viral infection. f Cd4-Cre:LepR^+/+ and Cd4-Cre:LepR^fl/fl mice were intranasally challenged with H1N1 influenza virus and virus-specific IgG1, IgG2b and IgG2c in sera were measured by ELISA 9 days post-infection (n = 7 per genotype) (IgG1: *P = 0.0183, IgG2b: *P < 0.0181, IgG2c: *P = 0.0168). Data are shown for individuals (dots) and mean (bars) values, and analysed by Mann–Whitney U-test (a–f). *P < 0.05, **P < 0.01. Results are representative of two independent experiments.