Abstract
Growth of the murine B-lymphocyte cell line CC9C10 and the myeloma SP2/0 was enhanced significantly by the presence of the unsaturated fatty acids, oleic and linoleic acids in serum-free culture. The cellular content of linoleic and oleic acids gradually increased during continuous culture passage, with no evidence of regulatory control. Over 10 culture passages in the presence of these fatty acids, the unsaturated/saturated fatty acid ratio of all cellular lipid fractions increased substantially. Most of the fatty acid accumulated in the polar lipid fraction (more than 74%) and only a small proportion was oxidized to CO2 (0.5%). Linoleic acid caused a decrease to one-eighth in the rate of metabolism of glutamine and a 1.4-fold increase in the rate of metabolism of glucose. There was no change in the relative flux of glucose through the pathways of glycolysis, pentose phosphate or the tricarboxylic acid cycle. The changes in energy metabolism were reversed when the cells were removed from fatty acid-supplemented medium. The most plausible explanation for these effects is the observed decrease in the rate of uptake of glutamine into cells loaded with linoleic acid. Growth of the CC9C10 cells in linoleic acid caused the Km of glutamine uptake to increase from 2.7 to 23 mM, whereas glucose uptake was unaffected.