Propionate regulates lymphocyte proliferation and metabolism

1. The effect of propionate on lymphocyte proliferation and metabolism was investigated. Lymphocytes obtained from human blood and rat mesenteric lymph nodes were utilized. 2. Propionate at concentrations of 0.04 and 1.0 mmol/l stimulated the amount of [3H]thymidine incorporated either in cultured human T lymphocytes or rat T and B lymphocytes. 3. Concentrations of propionate between 2 and 5 mmol/l caused a marked inhibition of lymphocyte proliferation. 4. This short-chain fatty acid was metabolized by these cells and produced succinate in significant amounts; however, its oxidation was low. 5. Propionate did not alter glucose, glutamine and pyruvate utilization and oxidation in incubated rat lymphocytes but increased the formation of lactate and aspartate. 6. In contrast, propionate inhibited by 50% the synthesis of lymphocyte lipid from [1-14C]acetate at concentrations of 0.5 and 1 mmol/l and reduced by half the incorporation of 3H2O into lipids at 1 and 5 mmol/l. 7. The results suggest that inhibition of lipid synthesis is a possible mechanism leading to reduction of lymphocytes proliferation.