The immunophenotypic characterization of bovine lymphomas.

A prospective analysis of 38 cases of bovine lymphoma was performed. Thirty-five of the lymphomas were considered enzootic because of serologic or molecular biologic association with the bovine leukemia virus (BLV). The three remaining cases were in cattle < 1 year of age and were not associated with BLV and hence were considered sporadic lymphomas. Utilizing the national cancer Institute Working Formulation for the morphologic classification of human non-Hodgkin's lymphoma, 54.3% (19/35) of the enzootic lymphomas were classified as the diffuse large cleaved cell type. The cells of the 35 enzootic lymphomas expressed a consistent immunophenotype represented by MHCII+, gamma-heavy chain+, and lambda-light chain+; this constellation of markers indicated a mature B-cell phenotype. The three sporadic lymphomas failed to express MHCII antigen despite the presence of other B-cell antigens. There was no correlation between morphologic cell type and immunophenotype in these bovine lymphomas.