Morphologic heterogeneity of human adult astrocytes in culture: correlation with HLA-DR expression.

Human adult astrocytes derived from brain surgical resections showed marked morphologic heterogeneity when cultured in vitro, ranging from a flat, fibroblast-like appearance to process-bearing cells with little soma cytoplasm. The majority of cells were intermediate in morphology, bearing a prominent cytoplasmic cell body with processes radiating from them. The morphologic heterogeneity was more extensive than that of adult rat astrocytes, and was not correlated with the extent of attendant gliosis in the surgical specimens, or the site of the surgical resection. None of the human astrocytes expressed A2B5, thus preventing their classification on basis of lineage into type 1 or type 2 astrocytes. However, functional differences appear to exist between subpopulations of human astrocytes, since the proportion of process-bearing human astrocytes that expressed HLA-DR in vitro was significantly greater than that found for flat astrocytes.