Abstract
Background: Based on earlier research, Rickettsia helvetica could possibly be involved in the pathogenesis of sarcoidosis. Rickettsiae are transmitted to humans by a tick vector, Ixodes ricinus; this tick is highly prevalent in Northern Europe. We aimed to investigate the association between evidence of rickettsiae and sarcoidosis in histological samples. Methods: We included formalin-fixed, paraffin-embedded mediastinal lymph node biopsies from 52 ethnic Danish patients with sarcoidosis and compared these with 50 biopsies from ethnic Danish patients with mediastinal lymphadenopathy of other causes. Samples were analysed for: (1) rickettsial DNA by real-time polymerase chain reaction (PCR) and (2) rickettsial rDNA (ribosomal DNA) by a specific fluorescence in situ hybridization technique (FISH). Results: Rickettsia was not detected in biopsies by real-time PCR and/or FISH analyses. Conclusion: Our results do not support the hypothesis that Rickettsia is involved in the pathogenesis of sarcoidosis.
Acknowledgements
The authors thank laboratory technicians Lisbeth Hein and Lone Højholt for their meticulous preparation of the samples. Preliminary results were presented as a scientific poster at the European Respiratory Society Annual Congress, Berlin, October 2008.
Declaration of interest: None of the authors have any financial involvement in any organization with a direct financial interest in the subject discussed in the submitted manuscript. The authors have no conflict of interest. The study was partly sponsored by Civil Engineer Johannes E. Ormstrup and wife Grete Ormstrup's Fund. The sponsor had no influence on the design of the study or interpretation of the data.