Direct ultrastructural evidence of lymphocyte-mediated cancer cell lysis in the microenvironment of Chinese nasopharyngeal carcinoma.

We observed 101 cases of Chinese nasopharyngeal carcinoma (NPC) with light and electron microscopy, focusing on the relationship between lymphocytes and cancer cells and their alterations during interaction. Cancer cells conjugated by lymphocytes showed injuries to varying degrees in 60% of cases with World Health Organization classification 2 + 3 NPC, but not in those cases with World Health Organization classification 1 NPC. The alterations of cancer cells conjugated by lymphocytes included loss of cell membrane and cytoplasm, degeneration of cell organelles, and even cell necrosis. Initial lesions of the cancer cell frequently occurred in the region infiltrated by lymphocytes. The lymphocytes could penetrate deeply into the cytoplasm, even into the nucleus of the cancer cell. At the same time, lymphocytes were themselves intact. The lymphocytes were classified into three groups: small lymphocytes, medium-sized lymphocytes, and blastoid type or transformed lymphocytes. The current study provided the direct ultrastructural evidence that lymphocyte-mediated cancer cell lysis might occur in the microenvironment of NPC and enabled us to summarize ultrastructural features of this phenomenon.