In vitro generation of CD19⁺CD20⁻CD38⁺CD27^hiCD43^hiCD138^+/−cells from proposed B-1 cells. The proposed B-1 cells were isolated as described in Figure 1 and were cultured for 5 days in the presence of R-848, IL-2, IL-10, IL-15, and IL-6. After culture, cells were stained for Live/Dead Fixable Aqua, CD19, CD3, CD20, CD27, CD43 CD38, and CD138, and analyzed by flow cytometry. Plots shown are from a representative experiment of 3.