Th2 cells degranulate eosinophils

T helper 2 cells are involved in allergen-specific adaptive immune processes and associated diseases such as asthma, but their interference with innate immune cells at sites of inflammation has been unclear. In the December 19/26 Nature, Kanade Shinkai and colleagues at the University of California San Francisco, USA, show that in vivo, helper T cells regulate the discharge of eosinophil granular contents and type-2 innate immunity (Nature, 420:825-829, December 19/26, 2002).

Shinkai et al. used Rag-1^-/- mice — which lack both B and T cells — to examine the capacity of the helminth Nippostrongylus brasiliensis to activate IL-4 expression from innate immune cells. They observed that in the absence of the immune cells, IL-4-expressing eosinophils were recruited to tissues infected with the parasite, but eosinophils failed to degranulate. Reconstitution with CD4 T cells promoted accumulation of degranulated IL-4-expressing cells, but only if T cells...