Photoreactivating enzyme induction in human lymphocytes.

Abstract

Abstract— Photoreactivating enzyme (PRE) activity was determined in human lymphocytes cultured in the presence or absence of the mitogen phytohemagglutinin (PHA). Photoreactivating enzyme activity increased from 0 to 12pmol/mg/h in about 40 h in cells cultured in the presence of PHA; enzyme activity was unchanged in the absence of PHA. The kinetics of induction of PRE and of lactate dehydrogenase, a marker of mitogenic stimulation, were indistinguishable, indicating that PRE induction results from stimulation of transcription and translation by the mitogen, rather than a specific effect of the PHA on PRE production. The level of PRE was also higher in mouse lymphoblasts growing rapidly in RPMI 1640 medium than in the same cells growing more slowly in Dulbecco's medium.