Figure 1.

CD11b⁻ and CD11b⁺ B1 cells are B cells, not T cells or monocytes. (A) Adult PBMCs from three separate donors were CD19 enriched and immunofluorescently stained for CD11b, CD20, CD27, and CD43. CD11b⁻ B1 cells (CD20⁺CD27⁺CD43⁺CD11b⁻) were sort-purified (Influx; BD) and evaluated postsort for expression of CD3 by flow cytometric analysis (LSRII; BD), and then compared with separately purified T cells, as indicated. (B and C) Adult PBMCs were CD19-enriched and immunofluorescently stained for CD11b, CD20, CD27, and CD43, as well as CD2, CD3, CD7, and CD8. The expression of T cell markers on naive (CD20⁺CD27⁻CD43⁻), memory (CD20⁺CD27⁺CD43⁻), and CD11b⁻ B1 (CD20⁺CD27⁺CD43⁺CD11b⁻) cells was evaluated by flow cytometric analysis and compared with T cells (CD3⁺CD20⁻), as indicated (B). B cells were gated to exclude CD3⁺ events, and the expression of T cells markers was evaluated on CD11b⁻ B1 cells by flow cytometric analysis and compared with T cells (CD3⁺CD20⁻), as indicated (C). (D) Adult PBMCs were immunofluorescently stained for CD11b, CD20, CD27, and CD43, as well as CD19, CD79a, and κ and λ light chains (combined). B cells were gated to exclude CD3⁺ events, and naive, memory, and CD11b⁺ B1 cells were then evaluated for expression of B cell markers by flow cytometric analysis and compared with T cells (CD3⁺CD20⁻) and monocytes (CD11b⁺CD3⁻CD20⁻), as indicated. (E) Adult PBMCs were CD19 enriched and immunofluorescently stained for CD11b, CD20, CD27, and CD43, as well as CD7. B cells were gated to exclude CD3⁺ events, and naive, memory, and CD11b⁺ B1 cells were then evaluated for CD7 expression by flow cytometric analysis and compared with T cells and monocytes, as indicated. (F) Sort-purified CD11b⁻ B1 cells, CD11b⁺ B1 cells, T cells, and monocytes were cytocentrifuged onto glass slides, stained with Wright-Giemsa, and examined by light microscopy. Representative images for each cell type are shown. Bars, 5 μm. Results shown in B–F represent one of three separate donors.