Periodic
CD19 is a member of the immunoglobulin super family with two immunoglobulin-like domains. It is a single-chain glycoprotein present on the surface of B lymphocytes and follicular dendritic cells of the hematopoietic system. CD19 is an important regulator of B-cell development, activation, and differentiation. On B cells, CD19 forms a signaling complex with CD21, CD81, and CD225 (Leu-13). CD19 is expressed from the earliest recognizable B-cell lineage, through development, to the B-cell differentiation stage, but is not expressed by mature plasma cells.
