Abstract
Four human and 4 rat astrocytomata and mammalian adult brain and spinal cord were examined by indirect immunofluorescence with human serum containing smooth muscle antibody. Cryostat sections of astrocytomata showed staining of the tumour cell cytoplasm and processes while in normal adult brain and spinal cord the entire astrocyte stained. Impression film and tissue culture monolayers of astrocytomata showed staining of cell processes and a fine, filamentous network in the cell body. The reaction with astrocytoma tumour cells was stronger than that with the corresponding normal astrocytes. Specificity of the staining reaction was established by its prevention on neutralization absorptions of the serum with extracts or homogeneous of smooth muscle. The presence of smooth muscle-associated antigen in astrocytes and astrocytomata is indicative of contractile protein providing a mechanism of cell movement in vivo.