A Cytochemical Study of Marrow Enzymes in Megaloblastic Anaemia

A cytochemical study of the enzyme content of megaloblasts compared with normoblasts under comparable conditions of erythroid hyperplasia has shown an increased activity of representative enzymes of the Embden-Meyerhof pathway, pentose phosphate shunt and tricarboxylic acid cycle in individual megaloblasts at all stages of maturation. The finding of a mixed population of cells with regard to enzyme content in late megaloblasts may be related to reported variations in prolongation of the intermitotic period at an earlier stage of maturation in megaloblasts. An increased cell content of soluble, NAD-linked, α-glycero-phosphate dehydrogenase in the megaloblast contrasts with reports of a selective decrease of this enzyme in homogenate studies of human and animal tumours which has been claimed to be a specific metabolic change in neoplastic cells.
It is concluded that the increased serum lactate dehydrogenase levels in megaloblastic anaemia are derived from the intramedullary destruction of large numbers of megaloblasts containing an increased amount of this enzyme.