B-lymphoproliferative disorders: a proposed unified pathogenetic pathway

5' Nucleotidase in chronic B cell leukemias: a cytochemical and ultrastructural study

We studied by cytochemical means the distribution of 5' nucleotidase (5' NT), a purine degradative enzyme, in the circulating lymphocytes of 24 healthy donors and 41 cases of chronic lymphoid leukemias, classified according to morphological and immunological criteria. About half the normal circulating lymphocytes were 5'NT positive and exhibited variable degrees of enzyme activity. Among chronic B lymphocytic leukemias we found high percentages of positive cells only in the phenotypically more mature cases. Moreover all cases of hairy cell, follicular cell, lymphoplasmacytic, and plasma cell leukemia showed moderate or weak 5' NT reactivity. Also one case of chronic T lymphocytic leukemia, CD8 positive, was moderately positive, while another, with large granular lymphocyte morphology, was completely negative. Electron microscopy revealed a discontinuous, granular plasma membrane reaction pattern, varying in intensity from case to case. In conclusion, our results confirm the usefulness of the 5' NT cytochemical reaction for identification of lymphoid populations at different stages of maturation in chronic B cell disorders.

Purine degradative enzymes in circulating malignant cells of patients with chronic B cell neoplasia

Previous reports have shown that the purine degradative enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and ecto-5'-nucleotidase (5'NT), play an important role in the normal development of lymphocytes and that investigations of these enzymes are of value in defining subsets of lymphoid malignancies of T-cell origin. Pharmacological inhibition of one of these enzymes has been found to be an effective treatment for a few lymphatic neoplasia. We have studied the activities of the above enzymes in the circulating malignant cells of 25 patients with B-chronic lymphatic leukemia (B-CLL), four patients with B prolymphocytic leukemia (PLL), seven patients with leukemic centrocytic lymphoma (CC), 18 patients with hairy cell leukemia (HCL) and 16 patients with immunocytoma (IC). For comparison, the blasts of nine patients with 'common' acute lymphatic leukemia (cALL) and normal T (n = 12) and B (n = 8) cells were simultaneously investigated. Despite morphologic similarity, the leukemic cells of the chronic B cell malignancies demonstrate different enzyme patterns. B-CLL is characterized by very low activities of all the enzymes ADA, PNP and 5'NT. In the cells of HCL the highest values of PNP are found. The leukemic cells of IC are characterized by low levels of ADA but moderate levels of PNP and high levels of 5'NT. Thus some of the entities of B malignancies show typical enzyme patterns which might be of importance in defining maturation stages of the disease. The differences in these enzyme patterns can also be made use of in therapy with enzyme inhibitors such as deoxycoformycin.

Purine degradative enzymes and immunological phenotypes in chronic B-lymphocytic leukaemia: indications that leukaemic immunocytoma is a separate entity

Investigations of the purine degradative enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and ecto-5'-nucleotidase (5'NT) have been shown to be of value in defining subsets of lymphoid malignancies. We have studied the activities of these enzymes in the circulating malignant cells of 35 patients with chronic B lymphocytic leukaemia and have correlated the biochemical data with immunological phenotypes. Classification of the cases into those without evidence of secretory activity ('true' CLL, 14 patients) and those with cytoplasmic immunoglobulin (CIg) ('immunocytoma'; 21 patients) revealed that immunocytomas are phenotypically and biochemically associated with more mature features. Malignant cells without CIg were characterized by low activities of ADA, PNP and 5'NT. In malignant cells with evidence of secretory activity (immunocytoma), low activity of ADA was also observed, but the activities of PNP and 5'NT were relatively high and approached the range of normal B lymphocytes. The differences in PNP (P less than 0.05) and in 5'NT (P less than 0.01) between these two groups were significant. Phenotypically the cells without CIg were predominantly associated with IgM (+k light chains) as surface membrane immunoglobulin (SmIg) whereas expression of IgG was more often observed in the leukaemic cells with CIg. No correlation between enzyme patterns and the stage of the disease was apparent. Thus both biochemical and immunological criteria show that cases of CLL vary within a range of maturity and that those with CIg might be more mature in the B cell axis. The present study emphasizes the value of purine enzyme studies in defining subsets of B cell neoplasia.