Inflammatory infiltrates and natural killer cell presence in human brain tumors

Immunohistochemical analysis of subpopulations of inflammatory cells in 81 primary and secondary human brain tumors was done. Natural killer (NK) cells, representing non-major histocompatibility complex-restricted, spontaneous cytotoxicity and monocytic cells are virtually absent in infiltrates of gliomas and account only for a minor percentage of inflammatory cells in brain metastases of carcinoma and in craniopharyngeomas. Infiltrates in gliomas consist almost exclusively of T-cells of the suppressor/cytotoxic type whereas infiltrates in carcinoma metastases and craniopharyngeomas contain considerable numbers of T-helper/inducer cells and B-cells. From this the authors conclude (1) that NK cells do not play a major role in tumor rejection, and (2) that the kind of inflammatory reaction does not depend upon the tumor site but more likely on the tumor type. No correlation between tumor differentiation and infiltrate composition is evident.