Human herpesvirus-8 genes are expressed in pulmonary inflammatory myofibroblastic tumor (inflammatory pseudotumor)

The presence of human herpesvirus-8 DNA sequences. as well os an overexpres sion of human interleukin-6 and human cyclin Di in myofibroblastic cells of inflammatory myofibroblastic tumor(inflammatory pseudotumor), has recently been reported. We describe the pattern of human herpesvirus-8 gene express ion in dye cases of pulmonary inflammatory myofibroblastic tumor. Reverse t ranscriptase-polymerase chain reaction (RT-PCR). with several positive and negative controls, was performed to detect mRNA of 11 open reading frames e ncoded by human herpesvirus-8 in lytic and Intent stages of viral replicati ve cycle. We found molecular transcripts from ORF16. ORFK13. and ORF72 in t he five cases and from ORFK2 in four of five neoplasms. The corresponding e ncoded proteins were human homologous oncoproteins (viral cyclin-D). inflam matory cytokines (viral IL-6). and inhibitors of apoptotic pathways (viral FLIP and viral Bcl-2), mostly expressed in a latent viral replicative stage . The rest of open reading frames examined included mainly lyric-associated genes and showed no expression. The spectrum of expressed viral genes is n ot the same as can be observed in Kaposi's sarcoma or multicentric Castlema n's disease, suggesting that human herpesvirus-8 plays a different role in the pathogenesis of its associated dis eases. These differences may be rela ted to either cell-specific or immunologic host factors.