B-cell colony growth of malignant and normal B-cells.

B-cell colony growth of malignant and normal B-cells has been studied in a double layer (agar-fluid) colony assay. Stimulatory factors consisted of irradiated blood leukocytes, phytohaemagglutinin (PHA), interleukin 2 (IL2) and 12-0-tetradecanoylphorbol-13-acetate (TPA) in various combinations. B-cell colonies have been obtained in all cases tested, i.e., 7/7 cases with chronic lymphocytic leukaemia, 7/7 cases with non-Hodgkin's lymphoma, 5/5 cases with hairy cell leukaemia and 7/7 normal B-cell suspensions, obtained from blood (X 3), bone marrow (X 2) and spleen (X 2). The plating efficacy ranged from 0.02-0.35, with a median of 0.07. Colony formation was found to be linear (r = 0.96) in the plating range of 0.5-8 X 10(5) cells. Secondary colonies could be obtained in 2 cases tested. DNA synthesizing cells in colonies were determined in 4 cases using monoclonal antibodies against DNA-incorporated bromodeoxyuridine (BrdUrd). In most cases the combination of PHA (with or without IL2) and irradiated leukocytes yielded the highest number of colonies, but in some experiments stimulation with TPA + IL2 was found to be optimal.