IL4 and asthma: Eosinophils extracellular traps were shown to promote Th2 immune response and correlate with the severity of asthma.15,53 It was recently reported that intratumoral eosinophils could activate CD8+ T cells and thus upregulates the effects of immune checkpoint blockade.54 To our knowledge, we provide the first evidence that splenic eosinophils and IL-4 functionally promote the CD8+ T cell memory response in bacterial infection.