Expression of macrophage inflammatory protein-1α in Schwann cell tumors

It is well known that tumors originating from Schwann cells often demonstrate degeneration, such as myxoid areas in Schwannoma (Antoni B) and granular cell tumors. However, the mechanism has never been understood in detail. Recruitment of circulating macrophages plays a role in degeneration, however, the factors leading to that process are not well known. Macrophage inflammatory protein-1alpha (MIP-1alpha), which belongs to the C-C family of chemokines, is thought to be involved in the recruitment of inflammatory cells and might play a role in the degenerative change of Schwann cell tumors. To elucidate the role of MIP-1alpha in such conditions, we employed immunohistochemistry and in situ hybridization analyses. Strongly positive staining of MIP-1alpha was revealed in the myxoid areas of tested tumors and in situ hybridization detected the existence of MIP-1alpha mRNA in some of the tumor cells. These results suggest that MIP-1alpha produced from tumorigenic cells plays a role in the auto-degenerative process of Schwann cell tumors. Furthermore, various levels of MIP-1alpha expression in these tumors were implicated to be correlated with histological variations.