Lactate dehydrogenase isoenzyme pattern: marker for differentiation of lymphocytes.

The lactate dehydrogenase isoenzyme pattern has been determined in different murine thymocyte cell populations. Enrichment of thymocytes with more mature cells through total irradiation results in a smaller percentage of LDH-1, LDH-2, LDH-3 and a greater percentage of LDH-4 and LDH-5. Fractionation of normal thymocytes by velocity sedimentation at unit gravity yields a fraction of cells with a high sedimentation rate. LDH-1 and LDH-2 formed a smaller percentage of the total enzyme activity in these cells. These findings indicate that the LDH isoenzyme distribution is a marker for differentiation of thymocytes.