Morphologic and functional characteristics of long-term cultures of murine myeloma cells

Murine myeloma cells proliferate well in cell culture even after up to 5 years in vitro and the globulin synthesized, as well as the ultrastructure, continues to be comparable to that of original tumor cells. Globulin synthesis by cultured cells from the C3H mouse tumor (x5563) ranged from 6 to 12.2 mg/g/48 hr and by cultured cells from Balb/c mouse plasmacytomas MOPC 21, 31C and 315 up to 40 mg/g/48 hr. This production is greater and occurs over a more prolonged period than those reported in other known published observations on globulin synthesis by normal or neoplastic cells from mice or other sources. However, both rate and quantity of globulin synthesis tend to decrease with time in vitro and this is inversely related to growth rate, which tends to increase with time in vitro. No evidence was found for increased globulin breakdown either intra- or extracellularly in these cultures.