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 end othelial 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 r epresent the tumour cells of KS. Objectives We aimed to investigate the expression of a wide variety of immu nohistochemic al 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 e ther laboratories. Methods Cells from six KS cell cultures derived from four subjects were exa mined by immunostaining. Results Comparison of these data indicates that KS-derived spindle cells ge nerally express myofibroblast antigens but lack. endothelial and/or leucocy te markers. Conclusions As the myofibroblast phenotype is not the predominant feature o f KS tissues, our findings further substantiate the view that the in vivo d ominant endothelial population represents a reactive hyperplasia rather tha n the true KS tumour process.