Elevation of antibodies to cytomegalovirus and other herpes viruses in pulmonary fibrosis.

The aim of this study was to determine whether latent viral infection is associated with idiopathic pulmonary fibrosis (IPF), an interstitial lung disease whose aetiology remains to be elucidated. Cytomegalovirus (CMV) immunoglobulin G (IgG) and complement fixation (CF), Epstein-Barr (EB) viral capsid antigen (VCA) IgG, herpes simplex virus (HSV) IgG, adenovirus CF, and parainfluenza 3 virus haemagglutinin inhibition (HI) titres were measured in the serum from patients with pulmonary diseases. The study included five subject groups: 35 normal controls (aged (mean +/- SD) 38 +/- 17 yrs); 43 IPF (63 +/- 10 yrs), seven collagen vascular disease-related interstitial pneumonitis (CVD-IP) (62 +/- 12 yrs); 22 sarcoidosis (36 +/- 14 yrs); and 17 emphysema (66 +/- 11 yrs). Levels of CMV IgG in IPF (87.6 +/- 51.7) and CVD-IP (101.2 +/- 69.9) were significantly elevated compared to those in the control (30.9 +/- 24.1), sarcoidosis (34.4 +/- 38.3) and emphysema groups (40.3 +/- 24.6), whereas CMV immunoglobulin M (IgM) was generally below the limit of detection. Similarly, CMV CF titres in IPF and CVD-IP were elevated compared to those in other diseases. EB VCA IgG titres in IPF, CVD-IP and emphysema and HSV IgG in IPF were also elevated. In contrast, adenovirus CF and parainfluenza 3 HI titres demonstrated no significant difference among all of the groups investigated. Increases in cytomegalovirus immunoglobulin G and complement fixation titres with negative cytomegalovirus immunoglobulin M suggest that latent cytomegalovirus infection may be more prominent in idiopathic pulmonary fibrosis or collagen vascular disease-related interstitial pneumonitis. Together with the elevation of Epstein-Barr virus viral capsid antigen and herpes simplex virus immunoglobulin G in idiopathic pulmonary fibrosis and/or collagen vascular disease-related interstitial pneumonitis, it is rational to assume that these viruses may be implicated in the development of pulmonary fibrosis. Further study is necessary to investigate the relationship between latent viral infection and pulmonary fibrosis.