An Fc engineered, humanized anti-CD19 monoclonal antibody directed against the B-cell-specific membrane protein CD19 with potential immunostimulating and antineoplastic activities. Anti-CD19 monoclonal antibody XmAb5574 targets and binds to CD19, thereby depleting and eliminating CD19-expressing B-cells. The modified Fc region of XmAb5574 increases binding affinity to Fc-gamma receptors of effector cells and thereby enhances antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cell-mediated phagocytosis (ADCP). CD19 is widely expressed during B-cell development, from pro-B-cell to early plasma cell stages.