LACTATE-DEHYDROGENASE AND ITS ISOENZYMES IN THE MARROW AND PERIPHERAL-BLOOD FROM HEMATOLOGICALLY NORMAL SUBJECTS

Lactate dehydrogenase (LDH) activity and its isoenzymatic fractions we re measured in bone marrow blood and in peripheral venous blood from 1 6 haematologically normal subjects. Total LDH activity was significant ly higher in marrow than in venous blood (428.8+/-98.4 vs 260.1+/-40.2 mU/l, p < 0.0001). The same was true for the absolute values of its i soenzymatic fractions. The percentage fractions LDH 1 and LDH 5 were s imilar in the two regions, while LDH 3 and LDH 4 were higher in medull ary blood (p < 0.05) and LDH 2 was higher in peripheral blood (p < 0.0 5). The Spearman test showed a limited correlation between marrow and peripheral total LDH activity values (p < 0.05). This seems to be at l east in part sustained by the highly significant correlations existing in LDH 3 and LDH 4 values, reported to be pre-eminent isoforms in mat uring haematopoietic cells (p < 0.005 and p < 0.001, respectively). Th ese findings could be attributed to an apoptotic regulation of marrow cell production.