Figure 4.

Immunofluorescence analysis of cell surface PIR expression. Bone marrow (BM), spleen (SP), and peritoneal lavage (PEC) cells from adult BALB/c mice were incubated first with aggregated human IgG to block FcγR, then stained with a combination of PE-labeled 6C1 anti-PIR and FITC-, CY-, allophycocyanin-, or biotin-labeled (and CY-labeled streptavidin) mAbs with the following specificity: Mac-1 and Gr-1 for myeloid lineage cells (first row); CD43 and B220 antigens for pro-B/pre-B cell compartment (second row); CD19 and IgM for B lineage cells (third row); CD3 and DX5 for T and NK cells and CD19 or Mac-1 for B cells and macrophages (fourth row); B220, CD21, and CD23 for marginal zone (MZ), follicular (FO), and newly formed (NF) B cells (fifth row); CD19, CD5, and Mac-1 for B1 and B2 subpopulations (sixth row). Staining of cells with light scatter characteristics of myeloid cells or small lymphoid and larger mononuclear cells was analyzed by flow cytometry. In the bottom two rows, B220⁺ or CD19⁺ B cells were examined for expression of the indicated cell surface antigens. The cell populations indicated by boxes in contour plots were examined for their expression of PIR molecules (solid line) versus background staining with an isotype-matched control mAb (dashed line). MFI indicates mean fluorescence intensity.