An unusual population of leukocytes was observed in the peripheral blood of a cow with a large tumor burden, using flow microfluorimetry. This new population accounted for 50% of the total cells in the peripheral blood of this animal. These cells expressed the p150,95 molecule (bovine CD11c equivalent), identified by the monoclonal antibody C5B6, a molecule found on myeloid cells and activated lymphocytes. The new population did not express the pan T molecules BoCD2 (the bovine T11 equivalent), BoCD5 (the bovine CD5 equivalent) or surface IgM. Isolated peripheral blood mononuclear cells maintained in bulk culture were able to kill autologous tumor cells and BHV-1 infected A549 in an NK-like assay. In vitro cytotoxicity by cells cultured from the peripheral blood of this animal was augmented 2- to 4-fold by the addition of IL-2.
Animals Cattle