To be eligible peripheral blood apheresis, all normal volunteers must have a hematocrit of greater than or equal to 36% and a peripheral platelet count of greater than or equal to 100,000/mm(3). Volunteers with a lymphoid/hematologic malignancy must have a hematocrit of greater than or equal to 30% and a peripheral platelet count of greater than or equal to 100,000/mm(3). All volunteers, including those volunteers with lymphoid/hematologic malignancies, must have a white blood cell count of greater than or equal to 4,000/mm(3). Volunteers with a lymphoid/hematologic malignancy must have a white blood cell count of less than 100,000/mm(3).