Serum rheumatoid factor levels linked to IgG4-related orbital inflammation

This retrospective study found that relapse of IgG4-related orbital inflammation was far more common in patients with high serum levels of rheumatoid factor than in patients with low levels of rheumatoid factor. Serum levels of rheumatoid factor reacted positively to corticosteroid treatment; however, the level eventually increased.

The authors examined orbital images and serum data from 24 patients before initiation of corticosteroid treatment and six months after discontinuation of treatment, and from six patients who received no treatment.

Seven patients, all with corticosteroid treatment, had elevated serum levels of rheumatoid factor. All 24 patients with corticosteroid treatment showed regression of the lesion, but one-third of these patients relapsed. The six patients without corticosteroid treatment showed minor proliferation or regression of the lesion at the six-month follow-up.

Serum IgG4 levels before and after corticosteroid treatment were not significantly different between those who relapsed and those who didn't, but the incidence of patients who were rheumatoid factor-positive was significantly higher among patients who relapsed (P = 0.02).

Furthermore, patients with serum levels of IgG4 > 900mg/dL also had significantly higher serum levels of soluble IL-2 receptor and blood eosinophilia. The mechanism underlying the elevation of serum IgG4 level was not determined but may reflect an increasing systemic immunologic imbalance.

They also note that several patients without high rheumatoid factor levels relapsed during the follow-up period. These results suggest that there are other risk factors for early relapse besides the serum rheumatoid factor level.