[Experimental study on the absorption mechanism of cryo-necrotized tumor antigens]

On day 7 of MRMT-1 tumor inoculation at the thigh in 5 week-old female SD rats, the tumor was treated cryosurgically by contact method at -170 degrees C and 2 cycle freezing. Postoperative changes in local blood circulation were observed by colloidal carbon perfusion and hydrogen-clearance methods, and pathway and time course of tumor antigen absorption were observed by measuring 3H-thymidine (injected intra-tumorally) uptake in various organs. The observations were done at 0.5, 1, 2, 3, 6, 9, 12, 24, 48, 72, 120 and 168 hour(s) after cryosurgery. The following results were obtained. At 0.5 to 1 hour after cryosurgery: vascular stasis, dilatation and tortuosity were observed. There were no inflow of colloidal carbon and almost no uptake of 3H-thymidine. At 6 hours: vascular stasis and sludging became more marked. There was no inflow of carbon, while uptake of 3H-thymidine was markedly increased. At 24 hours: some carbon inflows in fine vessels and partial recovery of blood circulation in the peritumoral region were observed. Rate of 3H-thymidine uptake was more increased. At 72 hours: carbon inflow and blood circulation were further increased, while the cryo-necrotized tumor showed hyaline degeneration. At 168 hours: increase of newly formed vessels and recovery of blood circulation were remarkable, but uptake rate of 3H-thymidine was decreased according to increased demarcation of the cryo-necrotized tumor. From the above results, it was suggested that the absorption of cryo-necrotized tumor antigens was starting through lymphatic channels in the early period, then also through newly formed capillaries surrounding the tumor at 24 hours after cryosurgery and continued until 72 hours after cryosurgery.