Cytochemical and Autoradiographic Investigations on Normal and Myelomatous Plasma Cells

Abstract

Cytochemically normal and myelomatous plasma cells show a negative peroxidase reaction, contain minute amounts of lipids, probably phospholipids and display an intense enzymatic activity when subjected to staining reactions for demonstrating dehydrogenases, cytochrome oxidase, acid phosphatase and non-specific esterase. Compared with normal plasma cells, multiple myeloma cells and the blast cells of 2 cases of plasma cell leukemia showincreased quantities of intracellular glycogen. With labelled DNA and RNA precursors and radioactive amino acid, normal plasma cells show decreasing DNA and RNA synthesis with progression of maturation, while protein synthesis becomes maximal in the more mature cell types. In multiple myeloma, thymi-dine incorporation is present in only a small percentage of cells, but their labelling intensity is generally high. Both leucine and uridine incorporation are low, although there is a wide range of variation from case to case. Myeloma cells also show a variable degree of RNA metabolic instability after treatment withactinomycinD. Myeloma cells may appear to be characterized by quantitative and/or qualitative defects in the formation of messenger RNAs, which may by responsible for the different level of differentiation reached in each case by the abnormal cell population.