Functional characterization of ecto-5'-nucleotidase-positive and -negative human T lymphocytes.
Functional studies were performed on human peripheral blood T lymphocytes stained with goat anti-5'-nucleotidase antibodies and separated into ecto-5'-nucleotidase (ecto-5'-NT)-positive and -negative populations using the FACSTAR fluorescence-activated cell sorter. On the average, ecto-5'-NT+ T cells contained 34 +/- 13% CD4+ and 55 +/- 15% CD8+ cells, whereas ecto-5'-NT-T cells contained 65 +/- 12% CD4+ and 23 +/- 8% CD8+ cells. Staining with anti-5'-NT antibodies did not significantly alter the ability of unseparated T cells to proliferate in response to PHA or PMA, or in a MLR. However, prior incubation with anti-5'-NT antibodies did inhibit the ability of irradiated T cells to provide help for PWM-stimulated Ig synthesis by as much as 55%. In five separate experiments, ecto-5'-NT-T cells demonstrated an equal or better ability to incorporate [3H]TdR after PHA stimulation or in a MLR, as compared with ecto-5'-NT+ T cells. Similarly, ecto-5'-NT- T cells were not diminished in their ability to provide help for autologous B cells in a PWM-driven system. Clearly, the inability of ecto-5'-NT- T cells from patients with a variety of immunodeficiency diseases to function in these assays cannot be explained solely by their lack of ecto-5'-NT activity. In contrast, ecto-5'-NT-positive and -negative T cells showed markedly different dose-response curves for proliferation in response to PMA. Ecto-5'-NT+ T cells responded to lower doses of PMA (1.0 ng/ml) than did ecto-5'-NT- T cells and showed a two- to eight-fold greater rate of [3H]TdR incorporation at 3 to 10 ng of PMA per ml. Ecto-5'-NT+ T cells may have a protein kinase C that is more accessible or more easily activated or may utilize an alternate pathway of activation when stimulated with low concentrations of PMA.
Thompson
L F
LF
Department of Immunology, Research Institute of Scripps Clinic, La Jolla, California 92037.
Ruedi
J M
JM
D015720:5'-Nucleotidase; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D009708:Nucleotidases / Q000276:immunology*; D010641:Phenotype; D010835:Phytohemagglutinins; D011043:Pokeweed Mitogens; D013601:T-Lymphocytes / Q000145:classification / Q000201:enzymology* / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000201:enzymology / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000954:Antigens, Surface; D007136:Immunoglobulins; D010835:Phytohemagglutinins; D011043:Pokeweed Mitogens; D009708:Nucleotidases; D015720:5'-Nucleotidase; D013755:Tetradecanoylphorbol Acetate