Mouse Th2 cells produce AR in response to TCR-mediated activation [27] , and the expression of AR by hemopoietic cells contributes to the clearance of a helminth parasite. However, our recent studies showed that basophils were the major human PBMC type that produced AR in response to anti-CD3/CD28 stimulation [31] , whereas production of AR by T cells was much lower. Therefore we examined human T cells in more detail, to determine whether human T cells could produce AR, and if so, whether this was produced preferentially by human Th2 cells.