Ecto-5'-nucleotidase (ecto-5'-NUC, EC 3.1.3.5., CD73) is a plasma membrane enzyme, which catalyzes the hydrolytic dephosphorylation of purine nucleotides to the corresponding nucleosides so that they can pass through the plasma membrane. The distribution of ecto-5'-NUC is heterogeneous, but all blood mononuclear cell (BMC) subpopulations investigated until now have had ecto-5'-NUC activity. Purified natural killer (NK) cells were prepared by fluorescence-activated cell sorting of CD16-positive cells (purity 94%). In purified NK cells the ecto-5'-NUC activity was less than 1 U/10(6) as estimated by a radioisotope method. Using a cytochemical assay, the proportion of cells with activity was less than 1%. The most likely explanation is that NK cells have no ecto-5'-NUC activity and that the very small ecto-5'-NUC activity observed in this study was caused by contaminating non-NK cells. NK cells thus constitute the only BMC subset known without ecto-5'-NUC activity.

5'-Nucleotidase↗

PubMedDate not supplied

Immunogenetics of rheumatoid arthritis and primary Sjögren's syndrome: DNA polymorphism of HLA class II genes.

We investigated the DNA restriction fragment length polymorphism (RFLP) of the Major Histocompatability Complex (MHC) class II genes: HLA-DRB, -DQA, -DQB, DPA, and -DFB in 24 patients with rheumatoid arthritis (RA), in 19 patients with primary Sjögren's syndrome (primary SS), and healthy Danes. The frequencies of DNA fragments associated with the following HLA class II genes were increased in RA when compared to normal controls: DRB1*04 (DR4) (relative risk, RR = 7.4, P less than 10(-3), DRB4*0101 (DRw53) (RR = 9.6, P less than 10(-3), DQA1*0301 (RR = 9.6, P less than 10(-3), DQB1*0301 (DQw7) (RR = 2.8, P less than 0.05, 'corrected' P greater than 0.05), and DQB1*0302 (DQw8) (RR = 4.5, P less than 10(-2). Negative associations were found between RA and DRB1*1501 (DR2/DRw15) (RR = 0.2, P less than 10(-2) and DQB1*0602 (DQw6) (RR = 0.2, P less than 10(-2), 'corrected' P greater than 0.05). The frequencies in RA of other HLA class II associated DNA fragments including DPA and DPB and the antigens DPw1-w6 defined by primed lymphocyte stimulation, did not differ significantly from those in controls. In primary SS, the frequency of HLA-B8 was significantly increased (RR = 9.0, P less than 10(-3). Positive associations were found between primary SS and DNA fragments associated with DRB1*03/13 (RR = 6.8, P less than 10(-3), DRB3*0101 (DRw52) (RR = 5.7, P less than 10(-2), DQA1*0501 (RR = 6.8, P less than 10(-3), DQB1*0201 (DQw2) (RR = 11.6, P less than 10(-5), and DQB1*0602 (DQw6) (RR = 2.7, P less than 0.05, 'corrected' P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗

PubMedDate not supplied

[Treatment of chronic lymphocytic leukemia with extracorporeal radiation of the blood].

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