IL5 and helminthiasis: Likewise, in allergen immunotherapy, through either anergy or deletion, Th2 cells decrease in number, reducing IL‐4, IL‐5 and IL‐13 production.136 Thus, hyporesponsive Th2 cells may share similar features in chronic helminth infection and tolerized allergic responses, however, whether this is an active process, and whether helminth infection causes hyporesponsiveness in bystander allergic responses in vivo is presently unclear.