Lactate dehydrogenase and its isoenzymes in the marrow and peripheral blood from haematologically normal subjects.

Lactate dehydrogenase (LDH) activity and its isoenzymatic fractions were measured in bone marrow blood and in peripheral venous blood from 16 haematologically normal subjects. Total LDH activity was significantly 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 isoenzymatic fractions. The percentage fractions LDH 1 and LDH 5 were similar in the two regions, while LDH 3 and LDH 4 were higher in medullary blood (p < 0.05) and LDH 2 was higher in peripheral blood (p < 0.05). The Spearman test showed a limited correlation between marrow and peripheral total LDH activity values (p < 0.05). This seems to be at least in part sustained by the highly significant correlations existing in LDH 3 and LDH 4 values, reported to be pre-eminent isoforms in maturing haematopoietic cells (p < 0.005 and p < 0.001, respectively). These findings could be attributed to an apoptotic regulation of marrow cell production.