AN ATYPICAL T-CELL LYMPHOSARCOMA IN A CALF WITH BOVINE IMMUNODEFICIENCY-LIKE VIRUS-INFECTION

An 11-month-old Holstein calf experimentally infected with bovine immu nodeficiency-like virus (BIV) developed T-cell lymphosarcoma 5 months postinoculation, concurrent with progressive monocytosis. Tumors were found in the thymus, multiple lymph nodes, and brain. Tumor cells were CD2(+), CD4(-), CD8(-) cells. Infectious BIV could be recovered from splenic tissue and blood mononuclear cells. Bovine leukemia virus was not present. Because this calf was part of an ongoing experiment on th e pathogenesis of BIV infection, immune function data were also availa ble both before and after lymphosarcoma developed. Neutrophil and mono cyte function were normal, but lymphocyte: blastogenesis was enhanced before the development of lymphosarcoma. Follicular hyperplasia in lym phoid tissues was also seen. This case raises the possibility that BIV infection may cause or be associated with some cases of atypical T-ce ll lymphosarcoma, without evidence of immune suppression at the time o f tumor onset.