Abstract
The cytotoxic effect of poly(rI).poly(rC) for interferon-treated cells is preceded by discrete ultrastructural alterations in (1) the mitochondria: swelling of the cristae and increased density of their matrix, (2) the nucleus: disorganization of the structure, and (3) the endoplasmic reticulum: slight dilatation with disorganization and depletion of the filament bundles. Our results do not allow us to conclude whether any of these alterations is a primary effect of the treatment. Possibly they are secondary to some, as yet unknown, functional defect, and only reflect incipient cell death.