Effect of surgery on tumour-directed leucocyte responses.

Leucocytes from 22 out of 26 patients with mammary carcinoma were significantly cytotoxic in vitro for cells cultured from mammary tumours though only two out of 17 of these preparations were cytotoxic for cells cultured from tumours arising at other sites. In the immediate postoperative period reactivity of patients' leucocytes with mammary tumour cells was undetectable but returned within one week of surgery. Leucocyte cytotoxicity may therefore offer a model in which the mechanism of postoperative depression of immunological competence may be investigated.