Attachment of IgG to dermal extracellular matrix in patients with fibromyalgia

Deposits of IgG localized to collagen bundles/extracellular matrix components occurred in skin biopsies from patients with primary fibromyalgia (PF). None of these patients demonstrated a positive lupus band test. Control skin biopsies from healthy controls were negative but showed intense reactivity for IgG after collagenase treatment. PF-skin attached both homologous and heterologous serum IgG in indirect immunofluorescence, which may point to a qualitative alteration of dermal matrix components in PF. Skin from patients with systemic lupus erythematosus and rheumatoid arthritis showed a lower dermal fluorescence intensity than in PF patients. The cause of the presence of IgG in dermal tissue from PF patients is unclear. It may be caused by a non-specific attachment of IgG to the extracellular matrix related, for example, to tissue hypoxia and/or increased capillary leakage due to an increased number of mast cells in the PF-skin.