[Characteristics and immunologic changes in patients with malignant brain tumors]

The investigation was concerned with assaying immunity and evaluating the role played by monocytes and tumor cells in the formation of T-cell dysfunction in malignant glioma (MG). The study group included 28 patients with anaplastic astrocytomas (n = 18) and glioblastomas (n = 10). MG patients showed significant changes in the numbers of CD16+ NK-cells and HLA-DR monocytes as well as lowered levels of HLA-DR expression on monocytes and proliferative response of T-lymphocytes as compared with both standard and alternative pathways of activation. Monocytes and macrophages suppressed T-cell activity due to production of prostaglandins E2 in such patients. Enhanced immunosuppression was also reported in 24-hour supernatants of tumor cells. Immune disorders were shown to involve apoptosis-independent mechanisms. Hence, despite the immune privilege of the brain, immunocompetent cells crossed blood-brain barrier and counteracted with tumor cells. As a consequence, monocyte function and cellular cooperation dropped while production of immunosuppressive factors rose, and T-cell dysfunction was brought about through apoptosis-independent mechanisms.