Successful regional immunotherapy with cell-wall skeletons of BCG and Nocardia rubra against autochthonous rat tumors.

Autochthonous tumors induced by 3-methylcholanthrene (MCA) in the thigh of Fischer 344 rats were treated by nonspecific immunotherapy with cell-wall skeleton of BCG (BCG-CWS) or Nocardia rubra (N-CWS) after incomplete radiotherapy. When MCA-induced autochthonous tumors grew to 3 cm in diameter, they were resected and autografted to the contralateral thigh. When the autografted tumors reached 1 cm in diameter, they were exposed to a single irradiation with 2000 rad giving rise to complete shrinkage in 16.6% of the cases. The rates of complete shrinkage were increased to 36.4% and 58.3%, respectively, by combined regional immunotherapy with BCG-CWS or N-CWS. Furthermore, immunoprophylactic effects of BCG-CWS and N-CWS were also detected in this experimental system.