ABSTRACT
BACKGROUND: Mouse regulatory T cells (Treg) may be deleted by intraperitoneal injection of anti-CD25 monoclonal antibody (mAb) (PC61). When Treg populations are thus suppressed, the immune system attacks tumours in autoimmune reactions. MATERIALS AND METHODS: An osteosarcoma (LM8) was transplanted subcutaneously into C3H/He mice. Serial injections of PC61 were conducted from seven days before (pre-PC61 group) or from two days thereafter (post-PC61 group) and tumour growth and metastasis were examined four weeks later. A control group received PBS injections. RESULTS: Subcutaneous tumours were reduced in size and the numbers of lung and liver metastatic colonies were significantly decreased in both pre- and post-PC61 groups compared to the control group. CONCLUSION: Tumour suppression was effective even when injection of PC61 was performed two days after LM8 transplantation. These results indicate that such treatments might be suitable to be applied in the clinic after surgical operations.
