Ecto-5′-Nucleotidase. II. Effect of 12-O-Tetradecanoylphorbol 13-Acetate on the Expression of Enzyme in Normal and Neoplastic B-Cell Lines

Abstract

Immature B-cells, including B-cell lymphoma lines, are often deficient in ecto-5′-nucleotidase (5′-NT) activity. 12-O-Tetradecanoylphorbol 13-acetate (TPA) was shown to be capable of inducing maturation toward plasmacytoid-like cells in immunoglobulin (Ig)-secreting B-celilines. An attempt was made to induce the enzyme in 5′-NT-negative B-cell lymphoma lines with TPA to clarify the relationship between 5′-NT and B-cell differentiation. After 3 days in the presence or absence of TPA, these cell lines were examined morphologically, and their 5′-NT activity, Ig secretion, surface Ig, and Ia, B₁, and B₂ antigens were estimated. Neither Ig secretion nor 5′-NT activity was induced by TPA in any of 4 nonsecreting cell lines studied. Ig secretion was significantly increased in 4 of 5 Ig-secreting cell lines. Two of these inducible cell lines, JD 38 and ST 486, became positive for 5′-NT activity and acquired morphologic characteristics of plasma cells after culture with TPA. The lymphoma cell line JD 38 was transplanted into nude mice and gave rise to a solid tumor. Although the tumor cells remained negative for 5′-NT, they could be induced by TPA to express both the enzyme activity and plasmacytoid-like appearance. These data suggested that in the Ig-secreting B-cell lymphoma lines, there was an association between the inducibility of 5′-NT and the capacity of these cell lines to undergo plasma-cytoidlike transformation in response to TPA.