Expression of class II major histocompatibility antigens on reactive astrocytes and endothelial cells within the gliosis surrounding metastases and abscesses.

To pursue the hypothesis that astrocytes may function as immunoregulatory cells, astrocytes within the reactive gliosis surrounding metastases and abscesses were examined for the expression of the class II major histocompatibility antigen HLA-DR. The tissue was analysed using single- and double-label avidin-biotin immunoperoxidase techniques employing monoclonal antibodies for HLA-DR (D1-12), macrophages (anti-Fc), T lymphocytes (2D3), glial fibrillary acidic protein (GFAP) and GFAP antiserum. Macrophages, astrocytes and T lymphocytes were present. The double label demonstrated HLA-DR on a large number of astrocytes. Taken together with evidence that astrocytes can release interleukin-1 and can present an antigen to lymphocytes, the finding of HLA-DR on these astrocytes supports their possible involvement in the cellular immune response.