Origin of spindle-shaped cells in Kaposi sarcoma.

Adult skin microvascular endothelial cells derived from new born foreskin were grown and maintained in tissue culture with and without dibutyryl cyclic AMP (DC-AMP) and isobutyl methyl xanthine (IMX). Whereas in the presence of DC-AMP and IMX, the cells showed the typical cobblestone appearance of endothelium, in the absence of these agents the cultured cells permanently converted to a spindle-shaped configuration. Because this phenomenon of transdifferentiation also occurs in the presence of specific cytokines, the profile of which is notoriously altered in acquired immunodeficiency syndrome (AIDS), the findings support the concept that in Kaposi sarcoma the spindle-shaped cells derive from dysfunction in the microvascular environment.