To be eligible for venipuncture or bone marrow aspiration, normal volunteers and volunteers with lymphoid/hematologic malignancies must have no history of an abnormal bleeding tendency or documented predisposition to infection. For venipuncture and bone marrow aspiration, the peripheral blood platelet count of normal volunteers must be greater than 100,000/mm(3) and for volunteers with a lymphoid/hematologic malignancy, the platelet count must be greater than or equal to 50,000/mm(3).