Evidence for the role of natural immunity in the control of metastatic spread of head and neck cancer.

Deficient natural killer (NK) cell activity may contribute to the development of distant metastases in the head and neck cancer patient. A total of 246 previously untreated patients expressed deficient NK activity against K562 target cells when compared to 110 age-matched healthy controls (70 +/- 48 lytic units (LU) versus 95 +/- 52 LU) (P less than 0.001). Some 164 consecutive patients have undergone definitive therapy subsequent to NK cell assessment and have been followed for a minimum of 12 months (median = 16 months), and 23 have developed recurrent disease in distant sites. The risk of subsequently (1) developing distant metastases, (2) developing regional metastases, and (3) dying of progressive cancer was inversely related to pretreatment NK LU values (P less than 0.02, less than 0.02, less than 0.005, respectively, by the Cox proportional hazards model). NK cell function within the peripheral blood of the patient with head and neck cancer could be related to the percentage of Leu 11+ NK cell subsets (P less than 0.01 by linear regression analysis) as determined by both single-parameter and multiparameter flow cytometric assessment. Contrastingly, no relationship could be identified between NK function with the percentage of circulating Leu 7+ cell subsets. In vitro measured NK cell function identifies a population at increased risk for developing distant metastases, thus supporting the role of natural immunity as defense mechanism against blood-borne disease.