Usefulness of monoclonal antibodies for detection of enzootic bovine leukemia cells.

Monoclonal antibodies against tumor-associated antigens (TAAs) expressed in the leukemic cells of enzootic bovine leukosis (EBL) were examined for their possible usefulness in detecting EBL tumor cells. The antibodies immunohistochemically reacted with EBL tumor cells and had cytotoxic activity against the cells but not against normal adult bovine peripheral blood lymphocytes (PBL) even after activation with mitogens. The TAA-positive EBL tumor cells also had B cell surface markers. The TAA was also found in several samples of PBL taken from BLV-infected healthy cattle (8 positive out of 81 tested), as well as in PBL from 13 out of 14 cattle with lymphocytosis but no evidence of tumor. Thus, monoclonal antibodies directed against TAAs might be a useful tool not only for diagnosing EBL but also for screening of BLV-infected cattle with the potential to develop tumors in the future.