{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CD19 is a human protein encoded by the CD19 gene. CD19 is expressed on follicular dendritic cells and B-cells; it is present on B-cells from earliest recognizable B-lineage cells during development to B-cell blasts, but is lost on maturation to plasma cells. In normal lymphoid tissue, CD19 is observed in germinal centers (on both B-cells and follicular dendritic cells), in mantle-zone cells, and in scattered cells in the interfollicular areas, with an overall immunoreactivity pattern similar to that of CD20 and CD22. However, in contrast to CD20, CD19 is also expressed in pre-B-cells. According to literature, CD19 is expressed in the vast majority of B-cell neoplasms."}]}]}