Natural killer activity in patients with breast cancer.

The clinical significance of the natural killer (NK) activity of peripheral blood mononuclear cells (PBMC) was analyzed in 83 breast cancer patients and 24 healthy control women. Similar levels of NK cytotoxic activity against K-562 target cells were found in PBMC from either untreated or surgically treated patients with local or disseminated breast cancer and from normal controls. However, a transitory and significant decrease (p less than 0.05) of the NK activity of PBMC from breast cancer patients was found during chemotherapy. But, according to quantitative flow cytometry analysis, similar percentages of phenotypically defined NK cells (CD16+, CD11b+, HNK-1+) were found in PBMC from patients, whether prior to or during chemotherapy, and healthy controls. Our results demonstrate that in breast cancer patients, the percentage of NK cells present in PBMC and their lytic activity are independent of the clinical and pathological stage of the disease.