CD63 and neoplasm: As we had previously demonstrated that eosinophils in WT mice upregulate markers of activation (CD69, CD35/CD21) and secretion (CD63) 14 days after EO771 tumor cell injection (Figure 4), we were interested in whether pulmonary eosinophils in IL5Tg lungs are similarly activated after i.v. EO771-GFP injection.