lymphocyte differentiation B cell differentiation B lymphocyte differentiation GO:0042115 Note that immunologists typically use the word 'development' to refer to cells of B or T cell lineages undergoing the process that GO describes as 'cell differentiation'. B-lymphocyte differentiation B-cell differentiation B cell development The process in which a precursor cell type acquires the specialized features of a B cell. A B cell is a lymphocyte of B lineage with the phenotype CD19-positive and capable of B cell mediated immunity. B cell activation