Depletion of eosinophils in mice through the use of antibodies specific for C-C chemokine receptor 3 (CCR3)

We have generated rat monoclonal antibodies specific for the mouse eotaxin receptor, C-C chemokine receptor 3 (CCR3). Several anti-CCR3 mAbs proved to be useful for in vivo depletion of CCR3-expressing cells and immunofluores cent staining. In vivo CCR3 mAbs of the IgG2b isotype substantially deplete d blood eosinophil levels in Nippostrongyus brasiliensis-infected mice. Rep eated anti-CCR3 mAb treatment in these mice significantly reduced tissue eo sinophilia in the lung tissue and bronchoalveolar lavage fluid. Flow cytome try revealed that mCCR3 was expressed on eosinophils but not on stem cells, dendritic cells, or cells from the thymus, lymph node, or spleen of normal mice. Unlike human Th2 cells, mouse Th2 cells did not express detectable l evels of CCR3 nor did they give a measurable response to eotaxin. None of t he mAbs were antagonists or agonists of CCR3 calcium mobilization. To our k nowledge, the antibodies described here are the first mAbs reported to be s pecific for mouse eosinophils and to be readily applicable for the detectio n, isolation, and in vivo depletion of eosinophils.