Lymphoreticular cells in human brain tumours and in normal brain.

The present investigation, using various rosetting assays of cell suspensions prepared by mechanical disaggregation or collagenase digestion, demonstrated lymphoreticular cells in human normal brain (cerebral cortex and cerebellum) and in malignant brain tumours. The study revealed T and B lymphocytes and their subsets (bearing receptors for Fc(IgG) and C3) in 5/14 glioma suspensions, comprising less than 15% of the cell population. Between 20-60% of cells in tumour suspensions morphologically resembled macrophages and less than or equal to 75% of these cells formed strong rosettes. Lymphocytes were not found in cancer-free (putatively normal) brain. Macrophages and the smaller "microglial cells" (both phagocytic, staining with sudan black, and expressing Fc(IgG) and C3 receptors) were found in normal brain in numbers similar to those in tumour suspensions, but with less rosetting avidity. These cells may be part of an immunological defence mechanism.