The screening of cattle with potential for developing leukemia by using monoclonal antibody against bovine leukemia cells.

Tumor cells from cattle with enzootic bovine lymphosarcoma (EBL) have a tumor-associated antigen (TAA) which is distinct from bovine leukemia virus (BLV)-induced antigens. We were able to sacrifice 8 TAA-positive cattle with no clinical signs of EBL and to examine whether or not they had gross or histological tumors. At necropsy, 4 animals had tumors macroscopically. Three animals had no tumors histologically but had initial lesions showing follicular hyperplasia and had the TAA on affected lymph nodes. The remaining one showed medullary hyperplasia in the spleen but there were no findings of tumors. These results suggest that most BLV-infected cattle which are TAA-positive but have no clinical signs of EBL, do have tumors and have a higher potential for developing EBL in the future when compared to BLV-infected but TAA-negative cattle.