200–500 μl of blood from adult mice were collected in EDTA-coated tubes (Becton Dickinson) and analyzed on a Bayer ADVIA 120 Hematology System by the Clinical Laboratories of Children's Hospital (Boston, MA). Manual leukocyte differential counts of >300 cells per sample were performed on Wright-Giemsa–stained blood smears. Cytocentrifuge preparations of the bone marrow and spleens of adult mice were also stained with Wright-Giemsa for microscopic evaluation.