Phenotypic characteristics of Kaposi's sarcoma tumour cells derived from patch-, plaque- and nodular-stage lesions: analysis of cell cultures isolated from AIDS and non-AIDS patients and review of the literature.

BACKGROUND: Kaposi's sarcoma (KS) is commonly thought to be derived from endothelial cells because of the predominant expression of endothelial markers in KS lesions. However, the heterogeneity of the spindle-cell compartment makes the precise lineage relationship of KS tumour cells unclear. Cultured KS-derived spindle cells constitutively overexpress antiapoptotic proteins and exhibit invasive properties, which suggests that they may adequately represent the tumour cells of KS.
OBJECTIVES: We aimed to investigate the expression of a wide variety of immunohistochemical markers by spindle cells derived from patch-, plaque- and nodular-stage lesions from patients with iatrogenic, sporadic and acquired immune deficiency syndrome-related KS, and to review the data reported by other laboratories.
METHODS: Cells from six KS cell cultures derived from four subjects were examined by immunostaining.
RESULTS: Comparison of these data indicates that KS-derived spindle cells generally express myofibroblast antigens but lack endothelial and/or leucocyte markers.
CONCLUSIONS: As the myofibroblast phenotype is not the predominant feature of KS tissues, our findings further substantiate the view that the in vivo dominant endothelial population represents a reactive hyperplasia rather than the true KS tumour process.