Pre-operative interleukin-2 immunotherapy induces eosinophilic infiltration in colorectal neoplastic stroma.

Interleukin-2 (IL-2) may induce peripheral eosinophilia and this phenomenon is related with response to IL-2 immunotherapy in patients with metastatic renal cell carcinoma. In previous experiences is reported that preoperative course with IL-2 may reverse the surgery-induced immunosuppression. This study's objective is to evaluate the histological changes of inflammatory infiltration in tumour stroma, in patients pretreated with IL-2 immunotherapy. 7 patients admitted to our surgical department with resectable recurrent colorectal cancer were treated with pre-operative course of IL-2; the tissue samples were analyzed for eosinophilic and inflammatory infiltration and compared with the samples obtained in the primary operation, performed without immunotherapy. In all patients were observed an increase of eosinophilic infiltration in tumour tissue. The mean increase were 200%, with high statistical significance (p < 0.0001). IL-2 pre-operative immunotherapy is able to change the interaction between host and tumour, by modifying the histological inflammatory infiltration in colorectal cancer tissue.