Immunohistochemical investigation of human leukocyte antigen (HLA)-DR-positive astrocytes in adrenoleukodystrophy brain.

We investigated immunohistochemically the expression of human leukocyte antigen (HLA)-DR in postmortem brain tissue of two adult patients with adrenoleukodystrophy (ALD). In addition to microglia and macrophages, a significant number of star-like cells were stained positively for HLA-DR in demyelinating lesions of both patients. Such cells congregated in the peripheral zone of the lesions. A mirror image analysis as well as double immunostaining for HLA-DR and glial fibrillary acidic protein established that these cells were a subset of reactive astrocytes. Together with other reports demonstrating that astrocytes express HLA-DR only under very limited conditions, the results of this study suggest the involvement of immune and inflammatory responses in the pathological processes of ALD.