Influence of irradiation on neutrophilic granulocyte function

BACKGROUND. Neoadjuvant radiotherapy is a common treatment modality for pat ients with Stage II and III rectal carcinoma but, after surgery, often is c omplicated by local infections. To define a possible influence of radiother apy on neutrophilic granulocytes in the neighborhood of tumor cells, the au thors investigated their function in vitro. METHODS. Density gradient-purified granulocytes from healthy donors were us ed for all tests. These cells were cocultured with the colon carcinoma cell line HRT-18 and irradiated. Their function was assessed by measuring lumin ol-enhanced chemiluminescence and migration against the chemoattractant for myl-methionyl-leucine-phenylalanine. RESULTS. Although irradiation decreased, the addition of tumor cells increa sed reactive-oxygen species release in granulocytes, which was enhanced fur ther by phorbol myristate acid (PMA), even after several hours, All contact s with tumor cells, however, caused immediate radical release that was inve rsely proportional to the radiation dose. Naive and irradiated cells were s timulated further by PMA. Migration of granulocytes clearly was inhibited b y tumor cells and irradiation, whereas the depth of invasion was enhanced b y higher doses of radiation. CONCLUSIONS. The current data show clearly that tile influence of radiother apy oil local defense against colorectal carcinoma is limited and cannot ex plain the increased rate of infectious complications. (C) 2001 American Can cer Society.