DNA polymerase γ, cytochrome c oxidase and mitochondrial integrity in rabbit spleen lymphocytes stimulated with concanavalin A

The activities of two mitochondrial enzymes: DNA polymerase γ and cytochrome c oxidase, have been compared with the kinetics of nuclear DNA synthesis and levels of the nuclear DNA polymerases α and β in rabbit spleen lymphocytes untreated or stimulated with concanavalin A (ConA). At early initiation of the culture, before the maximum increase of both the replicative α-polymerase and nuclear DNA synthesis, a simultaneous enhancement in the activities of the two mitochondrial enzymes was observed, just preceding and paralleling the expansion of the ATP pool. It is suggested that this is a reflection of increased mitochondrial activity providing the energy which results in an elevation of the concentration of dNTPs to values which are optimal for the replicative α-polymerase. During the later stages of incubation of lymphocytes, the activities of both DNA polymerase γ and cytochrome c oxidase decrease, paralleling a progressive loss of integrity of the mitochondrial structures within an increasing proportion of the lymphocyte population.