Characteristics of Reactive Microglia in Alzheimer’s and Parkinson’s Disease Brain Tissue
The brain has been believed to have an immunologically privileged status. Factors such as the absence of a lymphatic drainage, the restricted entry of globulins through the blood-brain barrier and a high tolerance to grafts appear to account for this view1. We suggest that brain responds in an appropriate fashion to immunological challenge and that microglia are resident representatives of the immune system. These cells express major histocompatibility complex (MHC) molecules, which are cell surface glycoproteins that play a significant role in the immune response. T-lymphocytes can interact only with cells expressing such MHC molecules. In Alzheimer’s and Parkinson’s disease brain, reactive microglia express the MHC class II molecule, HLA-DR2,3. HLA-DR is the major MHC glycoprotein involved in foreign antigen presentation to T helper/inducer lymphocytes.
KeywordsMajor Histocompatibility Complex Major Histocompatibility Complex Class Senile Plaque Major Histocompatibility Complex Molecule Double Immunostaining
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