Effect of treatment with the methanol extraction residue fraction of killed tubercle bacilli (MER) on the development of spontaneous pulmonary metastases from syngeneic implants of tumor 3LL in C57B1 mice.

Treatment of C57B1 mice with the methanol extraction residue fraction of killed tubercle bacilli (MER) shortly before or after surgical removal of a syngeneic implant of lung carcinoma 3LL reduced the incidence of spontaneous, fatally progressing pulmonary metastases in a large number of instances. Under certain conditions, the protective action of MER was pronounced and statistically significant. Small quantities of MER (0.2 mg) were optimally effective, when administered i.p. two days before or one day after excision of the initial implant.