Regression of bovine lymphosarcoma by treatment with cell-wall skeleton of Nocardia rubra.

Five bovine-leukaemia-virus-positive cattle with enlarged subcutaneous lymphatic nodules and having tumour-associated antigens (TAA) in their peripheral blood lymphocytes (PBL) were treated by injection of the cell-wall skeleton of Nocardia rubra (N-CWS) into the nodules. All treated animals received two or three injections of N-CWS (each 0.5-4 mg per nodule) at 2 or 4-week intervals. The effect of the treatment was evaluated by the size of the nodules. Complete regression of nodules was observed in seven out of ten nodules treated in five animals. Decrease of TAA-positive cells was also observed in their peripheral blood lymphocytes for all five treated animals. In one cow, the TAA-positive cells remained low for at least 280 days after treatment.