germinal center B cell Bm3 B cell A germinal center B cell that is rapidly dividing and has the phenotype IgD-negative, CD38-positive, and CD77-positive. Somatic hypermutation of the immunoglobulin V gene region can occur during proliferation of this cell type. Bm3 B cells are also reportedly CD10-positive, CD23-negative, CD39-negative, CD44-negative, CD71-positive, and CD77-positive. Bm3 B lymphocyte Bm3 B-cell Bm3 B-lymphocyte cell centroblast