Hu-Mik-beta1 to Treat T-Cell Large Granular Lymphocytic Leukemia

This study will examine the use of the humanized Mik-beta-1 (Hu-Mik-beta1) antibody in patients with T-cell large granular lymphocytic leukemia (T-LGL). Patients with T-LGL often have reduced white blood cells, red blood cells, and platelets, and increased numbers of abnormal cells called large granular lymphocytes (LGLs). Patients may have recurrent infections, anemia, or abnormal bleeding. Hu-Mik-beta1 attaches to LGL cells and blocks the action of growth factors called interleukins that stimulate LGL growth. Blocking these interleukins may stop T-LGL leukemia cells from growing. This study will determine the dose and frequency of treatment with Hu-Mik-(SqrRoot) 1 that can safely be given to patients to coat the surface of their leukemic cells with antibody, determine how long the antibody lasts in the blood after injection, and examine the side effects and possible benefits of the drug in these patients. Patients age 18 or older with T-LGL may be eligible for this study. Candidates will be screened with a medical history and physical examination, review of pathology studies, skin biopsy, evaluation of rheumatoid arthritis if present, chest x-ray, computerized tomography (CT) scans and other imaging studies as needed, bone marrow biopsy, and blood and urine tests. Participants will receive a single dose of Hu-Mik-beta1 by a 90-minute infusion through a vein. Groups of patients will be treated with increasing doses (0.5, 1.0, and 1.5 mg/kg) of the antibody. Patients who develop serious drug side effects are taken off the study. The treatment requires a 3- to 4-day hospital stay. In addition to Hu-Mik-(SqrRoot) 1 treatment, patients will undergo the following tests and procedures: * Collection of blood for 8 days following the dose of Hu-Mik-beta1 to measure blood levels of the antibody. * Follow-up visits of 1 to 2 days at 22, 29, and 43 days after the dose of the antibody and then every 3 months for a total of 9 months. * Bone marrow aspirate and biopsy if one