Establishment and selection of mAbs that react with mouse basophils but not with cells of other lineages in the bone marrow. (A) Culture supernatants of B-cell hybridomas established from rats immunized with mouse bone marrow basophils were screened for their ability to stain basophils (FcϵRIα⁺CD49b⁺ cells) but not other types of cells in the bone marrow. Bone marrow cells from C57BL/6 or BALB/c mice were reacted with hybridoma culture supernatants together with anti-FcϵRIα and anti-CD49b mAbs. The staining profiles of the C57BL/6 bone marrow cell fractions (R1, R2, and R3, as indicated) that were reacted with the representative hybridoma clone Ba103 are shown. Shaded histograms show the staining with isotype-matched control. Similar profiles were obtained when BALB/c bone marrow cells were analyzed with Ba103 (data not shown). (B) Bone marrow cells from C57BL/6 mice were stained with Ba103 in combination with each of the mAbs specific to the indicated surface markers. Data shown are representative of 5 repeated experiments. (C) Semiquantitative RT-PCR analysis for MMCP-8, MMP-9, EPO, and MBP was performed by using RNA prepared separately from Ba103⁺ cells, neutrophils (Siglec-F⁻Gr-1^high cells), and eosinophils (Siglec-F⁺Gr-1^med cells) in bone marrow. Data shown are representative of 3 repeated experiments.