Immunohistochemical Detection of Merkel Cell Polyomavirus in Kaposi's Sarcoma
M-T Fernandez-Figueras, E Musulen, C Carrato, G Sirera, D Lopez, C Ferrandiz, A Ariza. Hospital Universitari Germans Trias i Pujol, Badalona, Barcelona, Spain
Background: Both Kaposi's sarcoma (KS) and Merkel cell carcinoma (MCC) are more common in the elderly, transplant recipients and AIDS patients. Human herpesvirus 8 (HHV-8) is now acknowledged to be an infective cofactor in KS pathogenesis, whereas a novel polyomavirus (MCPyV) has been identified in MCC. Of interest, MCPyV has also been detected by real-time PCR in 3 of 49 (6.1%) KS cases, although in lower copy numbers than in MCC. Immunohistochemically, mAb CM2B4 detects MCPyV -associated protein with high specificity in most MCC cases. This study was designed to evaluate whether MCPyV can be immunohistochemically detected in KS.
Design: mAb CM2B4 immunostaining was performed on two tissue arrays of paraffin-embedded samples representing 78 KS cases, of which 29 corresponded to classic KS (C-KS) and 49 to AIDS-associated KS (AIDS-KS). mAb CM2B4 was generated against a predicted MCPyV antigenic epitope. Two arrays representative of 34 normal tissues and 36 MCC specimens were used as controls.
Results: Four cases of nodular stage C-KS contained CM2B4-positive cells. The immunoreaction was detected in fewer than 5% of cells and was predominantly faint. In contrast, 70% of MCC cases exhibited CM2B4 positivity in variable cell percentages and with different staining intensities. No normal tissue showed CM2B4-positive staining.
Conclusions: Although unable to provide conclusive evidence in support of MCPyV role in KS pathogenesis, the presence of MCCpV co-infection in four cases of nodal stage C-KS prompts interesting considerations as to its significance. It remains to be elucidated in further studies whether MCPyV is just a bystander for which KS cells provide a suitable proliferation milieu or, conversely, MCPyV infection contributes to local immunosuppression and favors KS development in otherwise healthy elderly patients. The authors wish to acknowledge Yuan Chang, MD for providing us the mAb CM2B4. This study was supported by grant FIS 02/0514.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 101, Wednesday Afternoon