Background IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that can affect nearly any organ (1). No detailed clinical and laboratory assessments have been reported in large numbers of patients with IgG4-RD diagnoses established by strict clinicopathological correlation (2-4).
Objectives To describe a single center cohort of 125 patients with biopsy-proven disease.
Methods We reviewed the baseline features of 125 patients with biopsy-proven disease. The diagnosis was confirmed by pathology review according to consensus diagnostic criteria (5). Disease activity and damage were assessed by the IgG4-RD Responder Index (RI) (6). Flow cytometry was used to assess levels of circulating plasmablasts (7, 8).
Results Of the 125 patients, 103 had active disease and 86 were on no treatment. Only 51% of the patients with active disease had elevated serum IgG4 concentrations. However, patients with active disease and elevated serum IgG4 concentrations were older, had a higher RI, a greater number of organs involved, lower complement levels, a higher absolute eosinophil count, and higher IgE levels compared to those with active disease but normal serum IgG4 (P<0.01 for all comparisons). The correlation between IgG4+ plasmablast level and RI (R=0.45, P=0.003) was stronger than that of total plasmablasts and RI. Seventy-six (61%) of the patients were male, but no significant differences according to gender were observed with regard to disease severity, organ involvement, or serum IgG4 concentrations. Glucocorticoids failed to produce sustained remission in the majority of patients.
Conclusions Nearly 50% of this patient cohort with biopsy-proven, clinically-active IgG4-RD had normal serum IgG4 concentrations. Serum IgG4 elevation identify a subset with more inflammatory features. IgG4+ plasmablasts correlate well with disease activity.
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Disclosure of Interest None declared