Establishment of animal liver metastatic model for C-1300 murine neuroblastoma and immunotherapy for it using OK-432, streptococcus preparation.

Intrasplenic administration of 1 x 10(6) C-1300 murine neuroblastoma cells induced spleen tumor in 78.6% of mice and liver metastasis in 64.3%. When mice were pretreated with carrageenan, an antimacrophage agent, the incidence of spleen and liver tumors in this system was lower, possibly due to the rebound increase in macrophage activity following the disappearance of the carrageenan effect. Continuous daily intraabdominal injection of 1 KE of OK-432 streptococcus preparation markedly reduced the appearance of liver metastasis (P less than 0.01), whereas the spleen mass was not reduced to such an extent. However, the survival rate of the OK-432-treated group did not differ greatly from that of the nontreated group. These results demonstrate the usefulness of the model of liver metastasis induced by intrasplenic administration of tumor cells and the effectiveness of OK-432 against liver metastasis formation.