Development and properties of a monoclonal antibody specific for human ecto-5'-nucleotidase.

After immunization with purified human placental ecto-5'-nucleotidase and fusion, 18 different hybrids were obtained which produce an antibody inhibitory for enzyme activity. These antibodies show complete cross-reactivity with the enzyme in a membrane-bound form or on the surface of intact cells. After cloning and ascites production, the antibody of one clone ( IFH - 5N1 ) was studied in greater detail. The IFH - 5N1 antibody is of the IgG 1 subclass. Optimal enzyme inhibition is 90% for purified 5'-nucleotidase and 80% for the enzyme on lymphoblasts. The specificity of this antibody is further demonstrated by enzyme inhibition assays and fluorescence labeling using various 5'-nucleotidase-positive and -negative human cells such as peripheral blood lymphocytes, leukemic cells, lymphoblastoid B- and T-cell-lines and fibroblasts. The antibody should provide a useful tool for the diagnosis of certain forms of acute leukemias and for the study of normal human lymphocyte subpopulations.