Soft-agar cloning of cells from patients with lymphoma.

Growth of cells from patients with lymphoma was promoted by feeder layers containing medium conditioned by adherent spleen cells of mineral-oil-primed BALB/c mice or by cells from a human B lymphocyte line (RPMI 1788). Sixty-five patients with all histologic types of non-Hodgkin lymphoma were studied. Lymphoid colony growth was obtained in 61% of bone marrows and 50% of lymph nodes histologically involved by lymphocytic lymphoma. Conversely, colony growth was observed in only a single instance from 49 bone marrows without overt lymphoma and was not observed in cultures of normal lymph nodes, spleens, bone marrows, peripheral blood, or thymuses. Colonies appeared within four days of plating and reached peak size in 7--10 days. Plating efficiency ranged from 0.001% to 0.1%. Morphological, histochemical, and immunological studies of cells from the colonies identified them as lymphoid, and sufficient evidence is available to designate the colony-forming units as putative lymphoma stem cells.