Figure 4.
IL-6 is necessary for protective response to an i.n. administration of heat inactivated influenza virus. (A, B): On day 16 of life mice received 5 × 105 EIU of heat-inactivated virus intranasally (Dk blue) or not (Lt blue). At 2 days after immunization, lungs were harvested and whole lung was used to extract RNA that was later assayed for RNA expression of IL-6 (A) and for TGFb (B) by QPCR. Each symbol represents one mouse. Shown is fold-change relative to unimmunized mice in a single experiment. The t-test was used to test for significant differences between groups. (C, D): Mice aged 14–17 days of life were i.n.-immunized (bold) with 5 × 105 EIU heat inactivated virus or left unimmunized (dashed). Three weeks later, all mice received a lethal dose of live virus. Y Axis, survival. X axis, day post challenge. (C) IL-6KO Female mice; i.n.-immunized, n = 11; unimmunized, n = 22. (D) Male mice; IL-6KO (red) i.n.-immunized, n = 16; unimmunized, n = 10. WT males (blue) i.n. immunized n = 11, unimmunized, n = 8). Shown is Mantel-Cox (log-rank) analysis of total data using % initial weight as noted in methods from 5 independent cohorts of mice receiving immunization and or challenge. Significance was set at p < 0.05.