Citrate synthesis by lymphocytes.

The important role of lymphocytes in humoral and cell-mediated immunity indicates that they need a readily available intracellular source of energy. Here, we demonstrate that these cells contain enzymes involved in citrate formation. The citrate is oxidized through the tricarboxylic acid cycle to furnish energy. A newly devised, simple radiometric method was used to determine the condensation of labeled acetate or acetyl CoA with oxaloacetate to form citrate. The de novo synthesized citrate was oxidized to pentabromoacetone, and radioactivity of the resulting CO2 was directly related to the amount of citrate synthesized. Both lymphocytes from chronic lymphatic leukemia patients and cultured lymphoblasts possess this active citrate-synthesizing apparatus, although the lymphoblasts appeared to have a considerably higher activity, perhaps because they are larger.