Distribution of ecto-5'-nucleotidase on subsets of human T and B lymphocytes as detected by indirect immunofluorescence using goat antibodies.

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Abstract
Human T and B lymphocyte subsets were characterized for ecto-5'-nucleotidase (ecto-5'-NT) expression by two-color immunofluorescence by using polyclonal goat antibodies to 5'-NT and murine monoclonal antibodies to T and B cell subsets. Anti-5'-NT antibodies were prepared by immunizing a goat with purified human placental 5'-NT. Lymphocyte surface 5'-NT was detected with F(ab')2 fragments of immune goat IgG followed by biotinylated F(ab')2 rabbit anti-goat IgG and fluorescein isothiocyanate-avidin. Lymphocyte cell surface antigens were detected with phycoerythrin (PE)-conjugated anti-CD3, anti-CD4, anti-CD8, anti-CD16, and anti-CD19. HB-4, an antigen present on a major subset of human peripheral blood B cells, was detected with murine monoclonal anti-HB-4 and PE-anti-mouse-kappa. Analysis showed that ecto-5'-NT was expressed on 32 +/- 7% of CD3+, 19 +/- 6% of CD4+, and 50 +/- 21% of CD8+ T cells, but not on CD16+ lymphocytes. Ecto-5'-NT was also expressed on 81 +/- 8% of adult peripheral blood B cells as defined by PE-anti-CD19; HB-4 was expressed on 84 +/- 7% of CD19+ cells. The two populations of B cells were not identical, however, because HB-4 was co-expressed on only 79 +/- 18% of ecto-5'-NT+ B cells. Two-color immunofluorescent staining of T cells from a patient with congenital agammaglobulinemia and low T cell ecto-5'-NT activity revealed reduced percentages of ecto-5'-NT+ cells in his CD3+, CD4+, and CD8+ populations. Thus, reduced ecto-5'-NT activity by enzyme assay was paralleled by reduced numbers of 5'-NT molecules on the cell surface. Two-color immunofluorescent staining of B cells from a patient with hypogammaglobulinemia and low B cell ecto-5'-NT activity also revealed markedly reduced expression of 5'-NT. HB-4 expression was normal, however, suggesting that the patient's B cells were blocked in maturation subsequent to the acquisition of HB-4 but prior to that of ecto-5'-NT. These results demonstrate that anti-5'-NT antibodies will be valuable tools for analyzing ecto-5'-NT expression and lymphocyte maturation in patients with immuno-deficiency diseases.