Monoclonal antibody analysis of major histocompatibility complex expression in human meningiomas.

Using monoclonal antibodies (MAB) in combination with the alkaline phosphatase anti-alkaline phosphatase technique, 20 meningiomas were examined for the expression of major histocompatibility complex (MHC) antigens. Most of the tumor cells were labeled with the MAB for class I MHC antigens. In addition, class I reactivity was seen in the tumor blood vessels, presumably reflecting labeling of the endothelial cells. Tumor cells and endothelium were not labeled with the MAB for class II MHC antigen HLA-DR. Occasionally a staining of periendothelial cells was detected. The presence of MHC antigens supports the assumption that endothelial cells play a role in antigen presentation, perhaps relevant to the initiation of an immune response, and that meningioma cells can be a target of T cell-mediated immune reactions.