APMIS : acta pathologica, microbiologica, et immunologica Scandinavica
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Monoclonal antibodies against ecto-5'-nucleotidase (ecto-5'-NT) have been clustered to CD73. The aim of the present study was to elucidate whether specific ecto-5'-NT activity on blood mononuclear cells (BMC) was correlated with CD73 expression measured by flow cytometry. During culture of CD73-negative lymphocytes the percentage of cells with ecto-5'-NT activity increased without there being a comparable increase in CD73 expression. ⋯ Treatment of BMC with phosphatidylinositol-specific phospholipase-C released 57% (51%-75%) of the ecto-5'-NT activity into the supernatants, without a detectable decrease in CD73 expression. The fact that ecto-5'-NT was removed from the supernatant after precipitation with anti-CD73 showed that the released ecto-5'-NT activity was due to enzymatic activity of CD73 molecules. The results of this study indicate that CD73 exists on BMC in isoforms with distinct capacities to bind mouse monoclonal anti-CD73.