Comparison of the effects of various immunosuppressive drugs on subrenal capsule assay (SRC assay)

We evaluated the effect of various immunosuppressive drugs in the SRC assay. We chose the most appropriate day to obtain the results of the SRC assay using the MBT-2 tumor. MBT-2 tumor-bearing mice of homogenic and heterogenic strains were separately given one of the three: cyclophosphamide, azathioprine or mizoribine. These drugs were evaluated on the 6th and the 11th day for the immunosuppressive effects expected from a host versus graft reaction. Concerning the homogenic mice that were injected with drugs, on the 11th day, the growth of the tumor was favorably suppressed in comparison with the growth of the control group (A-1) due to the anti-tumor effect of immunosuppressive drugs. We concluded that the 6th day was the most, appropriate day to obtain the results of this assay. Concerning the heterogenic mice, similar results were observed. In the mizoribine-group, we subcutaneously injected 200 mg/kg on alternate days. Yet the implanted tumor grew almost at the same rate as that of the A-1 group. In this group, a histological study showed reduction of the tumor cells and few inflammatory cells. We concluded that this drug was more useful than the others in the SRC assay and the suitable day for judgement was the 6th day.