Novel facts about an old marker: the LE cell.

For more than fifty years, lupus erythematosus (LE) cells were believed to result from in vitro opsonization of bare nuclei by serum antinuclear antibodies and their ultimate phagocytosis by neutrophils. Twenty years ago, we described that certain antinuclear antibodies could enter into viable cells, and later on, it was proved that penetration of anti-DNA antibodies into cells results in protracted active cell death. Recent findings indicate that the material engulfed by LE cells are apoptotic blebs as residuals of cells dying after penetration of anti-DNA antibodies. These observations not only change the interpretation of the presence of the LE cell phenomenon, but also stress the potential pathophysiological role of antibodies to intracellular antigens in autoimmune diseases.