ABSTRACT
From circulating immune complexes (ICs) of BLV-infected cattle, an antigen preparation was produced that contained some virus-specific proteins and a tumour-associated antigen. Eleven hybridoma clones were produced that secreted monoclonal antibodies (MoAbs) to this tumour-associated antigen, and two of them, MoAbs 1B4 and 1E9, were used in further studies. Most antibodies were of IgG1 subclass and showed no cytotoxic activity towards lymphocytes of BLV-positive cattle or to certain tumour cells. The MoAbs 1B4 and 1E9 recognized an antigen of about 75 kD on the cell surface of bovine lymphosarcoma cells and circulating lymphocytes from BLV-infected cattle with persistent lymphocytosis. The results presented indicate that the circulating immune complexes from BLV-positive cattle contain a tumour-associated antigen that is expressed on tumour cells and on lymphocytes from cattle with persistent lymphocytosis.
