Chronic lymphocytic leukemia (CLL) is a monoclonal hematopoietic disorder characterized by a progressive expansions of lymphocytes of B-cell lineage. These small, mature-appearing lymphocytes accumulate in the blood, bone marrow, lymph nodes, and spleen. CLL is a common leukemia in the wester world and accounts for 25% to 30% of adult leukemias. CD19,an integral membrane protein, is expressed by pro-B cells and functions as a co-stimulatory molecule that regulates mature B-cell activation and enhances B-cell proliferation. MDX-1342, a fully human monoclonal antibody, has demonstrated to specifically bind to human CD19 antigen with high affinity. Therefore, it is theorized that MDX-1342 will block activation of B cell stimulation, decreasing the number of cancerous B cell clones.