Natural Killer Cell Lysis of Head and Neck Cancer

This study analyzed the capacity of both fresh unseparated peripheral blood lymphocytes and enriched natural killer (NK) cells to lyse head and neck cancer cell lines. In a 6-hour chromium-release assay, only Leu-19⁺ NK cells mediated significant lysis. Furthermore, cell lines established from poorly differentiated cancers were more sensitive to lysis than were cell lines established from well-differentiated cancers. Cell lines from well-differentiated cancers also less readily inhibited K562 lysis in a cold-target inhibition assay, were not recognized by NK cells in a monolayer absorption assay (unlike poorly differentiated cancers), and failed to form conjugates with NK cells in a single-cell assay. These results indicated that deficient killing of a well-differentiated cancer cell vs a poorly differentiated cancer cell is partly a function of diminished NK cell recognition and tumor binding necessary to initiate lysis. As in previous studies regarding the prognostic implication of quantitated measures of NK cell activity within head and neck cancer patients, the results support the biologic relevance of the NK cell as a defense mechanism against metastatic disease, especially in patients with poorly differentiated, low major histocompatibility complex class I–expressing head and neck cancers.