Figure 6: CD4⁺ T cells are required for the maintenance of ILC2-induced immunity to N. brasiliensis.

(a) Number of N. brasiliensis larvae in the lung 2 days post primary infection (Nb), or after intranasal adoptive transfer of CD4⁺ T cells isolated from naïve mice or mice infected 29 days before transfer (n=5 mice, mean+s.e.m., representative of two independent experiments, ANOVA). (b) Number of N. brasiliensis larvae in the lungs of mice 2 days post primary infection (Nb) and i.v. reinfection (Nb+Nb), or after CD4⁺ T-cell depletion before primary infection (αCD4+Nb+Nb), and 7 days or 24 h before secondary infection (Nb+αCD4+Nb; n=5 mice, mean+s.e.m., representative of two independent experiments, ANOVA). (c) Number of red blood cells in the BALF of mice given a primary (Nb) or secondary (Nb+Nb) infection, and after CD4⁺ T-cell depletion 7 days before the secondary (Nb+αCD4+Nb). (d) Number of ILC2s in the lung of naïve mice or mice 2 days post secondary infection, with or without CD4⁺ depletion one week before reinfection (n=3–5, mean+s.e.m., representative of three independent experiments, ANOVA). (e) Number of IL-13⁺ ILC2s in the lung 2 days post challenge infection or with CD4⁺ depletion one week before reinfection (n=5, mean+s.e.m., representative of two independent experiments, t-test). (f) Mean fluorescent intensity of CD25 expression on lung ILC2s, as in e. (g) Differential larvae number in the airways and lung parenchyma of mice with primary (Nb) or i.v. reinfection (Nb+Nb), after CD4 depletion and/or intraperitoneal IL-2C treatment for 7 days before challenge (n=5, mean+s.e.m., representative of two independent experiments, ANOVA). (h) Number of ILC2s in the lungs of i.v.-primary infected (Nb) or reinfected (Nb+Nb) mice, and with CD4 depletion and IL-2C treatment for 7 days before challenge (n=5, mean+s.e.m., ANOVA). NS, non-significant; P>0.05; ^▪P<0.07; *P<0.05; **P<0.01; ***P<0.001; ****P<0.0001.