To measure the serum levels of IgG anti-Chlamydia pneumoniae (C. pneumoniae) and human heat shock protein (hHSP) 60 antibodies in patients with active giant cell arteritis (GCA) and to determine whether such levels decrease with corticosteroid therapy and remission of symptoms.
IgG anti-C. pneumoniae and anti-hHSP60 antibodies were quantified by commercial and in-house ELISA tests, respectively, in serum samples from 17 GCA patients, 39 polymyalgia rheumatica (PMR) patients and 23 age-matched healthy subjects.
Serum IgG anti-hHSP60, but not anti-C. pneumoniae, antibodies were significantly increased in GCA patients in comparison with PMR patients or healthy controls. After steroid therapy, both anti-hHSP60 and -C. pneumoniae antibodies decreased significantly in both groups of patients.
Although some infectious agents have been suggested to participate in GCA pathogenesis, our data do not suggest that C. pneumoniae might be one of them. The production of anti-hHSP60 antibodies is shared in GCA with other systemic diseases and may be triggered by unknown infectious agents and/or other inflammatory factors.