Lymphocyte lactate dehydrogenase isoenzymes in association with depressed mitogen responsiveness.

Purified lymphocyte preparations from cancer patients were less responsive to the mitogen phytohaemagglutinin (PHA) than were lymphocytes from healthy donors as measured by [3H]-thymidine uptake over periods in culture up to 96 hours. The uptake of radiolabel was paralleled by total cellular lactate production. The isoenzymic composition of lactate dehydrogenase (LD) in lymphocytes from healthy individuals was altered following PHA stimulation with increasing proportions of LD-1 and LD-2 throughout the culture period. This phenomenon was markedly reduced in lymphocytes from cancer patients. This defect in lymphocytes from cancer patients is thought to reflect an impaired capacity to accomplish an early mitogen-induced enhancement of glucose metabolism, which is a prerequisite for lymphocyte proliferation.