Rapidly progressive classic Kaposi sarcoma in an adolescent: response to interferon alfa therapy and biological correlates

Plasmacytoid dendritic cells in skin lesions of classic Kaposi's sarcoma

Plasmacytoid dendritic cells (pDCs) are the most potent producers of type I interferons (IFNs), which allows them to provide anti-viral resistance and to link the innate and adaptive immunity by controlling the function of myeloid DCs, lymphocytes, and natural killer cells. pDCs are involved in the pathogenesis of several infectious [especially viral, such as Molluscum contagiosum (MC)], inflammatory/autoimmune, and neoplastic entities. Kaposi's sarcoma (KS) is a multifocal, systemic lympho-angioproliferative tumor associated with Kaposi's sarcoma-associated herpesvirus (KSHV) infection. Microscopy typically exhibits a chronic inflammatory lymphoplasmacytic infiltrate in addition to the vascular changes and spindle cell proliferation. Despite the extensive research done on the immune evasion strategies employed by KSHV, pDCs role in relation to KS has only rarely been investigated. Given this, we intend to investigate pDC occurrence and activity in the skin lesions of KS. Immunohistochemical staining for BDCA-2 (specific pDC marker) and MxA (surrogate marker for local type I IFN production) was performed on classic KS (n = 20) with the control group comprising inflamed MC (n = 20). As expected, BDCA-2+ pDCs were present in abundance with diffuse and intense MxA expression (indicative of local type I IFN production) in all inflamed MC cases (20 of 20, 100 %). Though present in all the KS cases, pDCs were significantly less abundant in KS than in inflamed MC cases, and MxA expression was patchy/weak in most KS cases. In summary, pDCs are part of the inflammatory host response in KS; however, they were generally low in number with decreased type I IFN production which is probably related to KSHV's ability to evade the immune system through the production of different viral proteins capable of suppressing IFN production as well as pDC function.

Relationship between human herpesvirus 8 loads and disease stage in classic Kaposi sarcoma patients

Human herpesvirus 8 (HHV-8), also known as Kaposi sarcoma (KS)-associated herpesvirus, is causally implicated in all forms of KS, including the classic form. Our objective was to investigate the relationship between HHV-8 load in peripheral blood mononuclear cells (PBMCs) and the stage of the disease in classic KS (CKS) patients. HHV-8 loads were measured in 41 PBMC samples from CKS patients with different Krigel-based classification stages using a quantitative real-time polymerase chain reaction assay. Low HHV-8 DNA loads reaching a maximum of 75.5 copies/10(5) cells were detected in 73.2% of the patients. HHV-8 loads in patients with stages I and II were similarly distributed. An increased detection rate of HHV-8 DNA, although not statistically significant, was evident in patients diagnosed with CKS stages III and IV. We conclude that the measurements of HHV-8 load in PBMCs provide a limited correlation with the clinical stage of KS.