Proliferation and apoptosis in the evolution of endemic and acquired immunodeficiency syndrome-related Kaposi's sarcoma

Kaposi's sarcoma (KS) is a multifocal lesion that occurs predominantly in t he skin, most frequently in people infected with HIV-1, and that evolves th rough early stages (patch and plaque) to a tumor-like late stage (nodular). Both, endemic African (EKS) and AIDS-associated (AKS) KS expressed human h erpesvirus 8 (HHV-8) as shown by PCR. By immunohistochemistry the expressio n of cellular Bcl-2 and c-myc was confined in early stages of both EKS and AKS to relatively few endothelial cells (EC) whereas in nodular KS most of spindle cells (SC) strongly expressed both genes. CD40 was usually strongly expressed in SC at all KS stages as well as in EC of non-involved tissue w hereas CD40L (CD154) was not demonstrable. Fas (CD95) was moderately to wea kly expressed by SC whereas p53 and Waf-1 were found in less than 5% of the SC. In both AKS and EKS at nodular stage almost no apoptotic SC were detec ted. In most AKS and EKS low levels of cell proliferation were seen but AKS showed consistently higher values compared to EKS. All clinical types and stages of KS showed a diploid cellular DNA content by flow cytometric analy sis of microselected lesions. Thus, we conclude that KS during evolution re presents diploid, probably reactive, cell proliferation, which progressivel y increases the expression of strong cellular and also viral (HHV-8) antiap optotic factors.