Human herpesvirus 8 variants in sarcoid tissues

Summary Background The cause of sarcoidosis is unknown, although mycobacteria have been implicated. We examined sarcoid tissues for human herpesvirus 8 (HHV-8) in addition to mycobacterial genomic sequences. Methods Biopsy samples from 17 patients with sarcoidosis were studied (eight transbronchial, 27 lymph node, two skin, and two oral mucosa). We used tissues (n=137) from 96 patients without sarcoidosis as negative controls. A nested PCR was applied to amplify a segment of open reading frame (ORF) 26 of the HHV-8 genome, and a heminested PCR was used to amplify a segment of ORF 25 of HHV-8 and of the 16 S rRNA gene of mycobacteria. Differences in base sequences of the amplified fragments were resolved with single-strand conformation polymorphism and dideoxy sequencing. Findings HHV-8 ORF 26 DNA was detected in significantly higher proportions of sarcoid than of non-sarcoid tissue samples from lung (8/8 vs 0/54; p·0·0001), lymph nodes (26/27 vs 6/29; p·0·0001), skin (2/2 vs 0/17; p=0·006), and oral tissues (2/2 vs 1/13; p=0·029). 31 (82%) of the 38 ORF 26 DNA-positive sarcoid specimens were also positive for ORF 25 DNA. For mycobacteria-like 16 S rRNA DNA, the proportion positive was significantly higher in sarcoid than non-sarcoid tissues for lymph node samples (11/27 vs 2/29; p=0·003) but not for other tissues (lung 3/8 vs 22/54; skin 2/2 vs 15/17; and oral tissues 1/2 vs 0/13). Overall, the prevalence of HHV-8 ORF 26 sequences was higher in sarcoid tissues than in non-sarcoid tissues (p Interpretation Variant HHV-8 DNA sequences are found in a wide range of sarcoid but not non-sarcoid tissues. Mycobacteria-like 16 S rRNA sequences are more frequently present in sarcoid lymph nodes and not in other tissue types, but do not indicate infection by a particular mycobacterial species.