Development and characterization of a human monoclonal antibody probably detecting the leukocyte differentiation antigen CD39.

A human monoclonal IgM antibody, referred to as TU223, has been produced. The reactivity of TU223 was tested in various cells and cell lines by complement-dependent microcytotoxicity test and fluorescence-activated cell sorter analysis. The antigen defined by TU223 was expressed on Epstein-Barr virus-transformed B-cell lines and on some Burkitt's lymphoma cell lines, but was not expressed on normal T cells, B cells or erythrocytes. In addition, expression of the antigen defined by TU223 was also induced on B cells activated by Epstein-Barr virus or pokeweed mitogen, and on T cells activated by phytohemagglutinin, concanavalin A, pokeweed mitogen or recombinant interleukin-2. However, no expression of the antigen detected by TU223 was induced at all on recombinant interleukin-4-treated B cells or macrophage-like cell line U937. When the ability of TU223 and various mouse monoclonal antibodies to bind to human differentiation antigens was compared, interestingly, the reactivity of TU223 was found to be very similar to that of mouse monoclonal antibody CD23 (H107), which reacts with Fc epsilon receptor II. Two-color analysis revealed that the antigen defined by TU223 is expressed on the cell surface of certain lymphoid cells expressing CD23 antigen. However, it can be concluded that the antigen defined by TU223 is clearly distinct from Fc epsilon receptor II, based on assay of cross-blocking between H107 and TU223. The surface antigen on B85 cells recognized by TU2232 had the molecular size of 80-82 kiloDaltons as determined by immunoblotting analysis.(ABSTRACT TRUNCATED AT 250 WORDS)