The monoclonal antibody (MAB) CD 68 allows the immunocytochemical identification of macrophages in primary and metastatic brain tumors in paraffin embedded tissues.

While using the MAB CD 68 applied to paraffin embedded tissue specimen, macrophages could be marked in 31 primary brain tumors of glial origin and in 17 metastatic tumors from which 7 were carcinomas of the lung, 5 carcinomas of the breast, 2 from the digestive tract and 3 were clear cell carcinomas of the kidney. Despite quantitative differences between the primary and metastatic tumors in all specimen examined macrophages were found. The macrophages were localized within the tumor tissue, at the periphery of the tumor and its surroundings. In some cases cells with an intensive staining reactions were visible in blood vessel walls. No correlation between the type of tumor and intensity of macrophages infiltration has been found, however there were quantitative differences between primary and metastatic tumors.