[An experimental study on the induction of anti-tumor immunological activity after cryosurgery for liver carcinoma, and the effect of concomitant immunotherapy with OK432].

: Cryosurgery on liver carcinoma (MRMT-1) in rats and pre-operative administration of OK432 were performed in order to study host immunological response and the effect of immunotherapy before cryosurgery, respectively. Rats were divided into five groups, by treatment given: control, false-operative, incomplete-frozen, complete-frozen and complete-frozen + OK432-administrated groups under several conditions. In the incomplete-frozen group, the survival days significantly prolonged as compared with controls. Phytohemagglutinin (PHA) blast formation and CD4 positivity exhibited high levels at 8 weeks after cryosurgery. In the complete-frozen group, survival time was not prolonged and 3 cases of early death were observed. Moreover, CD4 positivity decreased at 3 days and CD8 positivity increased at 2 weeks after cryosurgery, significantly. On the other hand, in the complete-frozen + OK432-administrated group, CD4 positivity decreased gradually after cryosurgery. In contrast, PHA blast formation was significantly high at 8 weeks and the rise of CD8 positivity in the complete-frozen group was significantly suppressed with OK432 to a value of 31.8 +/- 4.1%. In addition, the survival time showed a prolonging tendency, with the exception of 2 cases of early death. From these results, we concluded that immunological response after cryosurgery for liver carcinoma may be induced by changes in cell immunity, and it was suggested that combination therapy with cryosurgery and preoperative immunotherapy might be effective.