Ecto 5'-nucleotidase deficiency in primary hypogammaglobulinaemia

Patterns of adenosine deaminase, ecto-5'-nucleotidase, poly(A)polymerase and surface light chain expression in chronic lymphocytic leukemias

The levels of activity of three enzymes have been measured in the circulating malignant lymphocytes of 47 patients with B chronic lymphocytic leukemia (CLL). These were the purine degradative enzymes, adenosine deaminase (ADA) and ecto-5'-nucleotidase (5'NT) and the enzyme responsible for the polyadenylation of mRNA, poly(A) polymerase. The patterns of activity of the above enzymes and the expression of surface immunoglobulin light chains were examined. A heterogeneity in the specific activity of the enzymes was observed which could not be attributed to variations of the percentage of B lymphocytes. A positive correlation was found between ADA and poly(A)polymerase activity (r = 0.383, p less than 0.01). Furthermore, the expression of immunoglobulin light chain phenotype was inversely related to 5'NT specific activity; CLL cases in which less than 20% of the cells expressed lambda chain phenotype, presented 5'NT specific activity of 16.7 +/- 3.3 (S.E.) nmol/h/10(6) cells, whereas in CLL cases with more than 20% of the cells expressing this phenotype the enzyme specific activity was 4.8 +/- 1.6 (S.E.) nmol/h/10(6) cells (p less than 0.02). These findings suggest that the simultaneous determination of enzymatic activities and immunological markers, might be useful in defining subsets in CLL and the subsequent clinical treatment.

Ecto-5'-nucleotidase activity in human T cell subsets. Decreased numbers of ecto-5'-nucleotidase positive cells from both OKT4+ and OKT8+ cells in patients with hypogammaglobulinemia

T lymphocytes from control subjects were separated into subsets using monoclonal antibodies of the OKT series and complement lysis and analyzed for ecto-5'-nucleotidase activity both by quantitative radiochemical assay and a histochemical stain. T cells from 15 control subjects contained 54+/-4% OKT4(+) (helper/inducer) cells and 32+/-3% OKT8(+) (cytotoxic/suppressor) cells. Total T cell ecto-5'-nucleotidase activity was 10.9+/-2.1 nmol/h per 10(6) cells with 25+/-7% positive by histochemical stain. Ecto-5'-nucleotidase activity in OKT4-enriched populations was 5.43+/-1.8 nmol/h per 10(6) cells with 14+/-2% positive by histochemical stain; that in OKT8-enriched populations was 17.1+/-5.9 nmol/h per 10(6) cells with 35+/-8% positive by histochemical stain. Two of four patients with congenital agammaglobulinemia and four of seven patients with common variable immunodeficiency had decreased proportions of OKT4(+) T cells with corresponding increases in the proportions of OKT8(+) T cells (OKT4/OKT8 = 0.60 to 1.0 as compared with 1.7+/-0.2 for control subjects). All four patients with congenital agammaglobulinemia, and three of seven patients with common variable immunodeficiency also had low T cell ecto-5'-nucleotidase activity (<5.5 nmol/h per 10(6) cells). Ecto-5'-nucleotidase activity in OKT4- enriched populations isolated from four patients with low total T cell activity was 2.85+/-0.90 nmol/h per 10(6) cells with 10+/-4% positive by histochemical stain; that in OKT8-enriched populations was 6.82+/-1.7 nmol/h per 10(6) cells with 7.5+/-3% positive by histochemical stain. Thus, the number of ecto-5'-nucleotidase positive cells is decreased, especially in the OKT8(+) subpopulation, and the low total T cell ecto-5'-nucleotidase activity seen in these patients is due to fewer positive cells rather than to substantially less activity per cell. Our data indicate that ecto-5'-nucleotidase activity defines two subpopulations of T lymphocytes (ecto-5'-nucleotidase positive and negative), the proportions of which are markedly altered in many patients with hypogammaglobulinemia. In preliminary studies with seven patients, increased numbers of ecto-5'-nucleotidase negative T cells appeared to correlate with increased suppressor T cell activity toward in vitro immunoglobulin synthesis. Therefore, ecto-5'-nucleotidase may be a useful cell surface marker in the study of imbalances of regulatory T cell subsets in patients with antibody synthesis disorders.