IgG4-IgE complex in patients with IgG4-related disease

Background IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disease characterized by high IgE levels; however, the physiological significance of elevated IgE levels in patients with IgG4-RD is unclear. Previously, we reported the formation of IgG4-IgE complex in IgG4-RD patients with elevated IgE levels. In this study, we examined the frequency of this complex formation and its relationship with the clinical features in IgG4-RD patients. Methods The IgG4-IgE complex was evaluated in 33 and 17 patients with and without IgG4-RD, respectively. The IgG4-IgE complex was evaluated by performing the immunoadsorption of IgG4 using anti-IgG4 antibody-conjugated matrices. Results The frequency of IgG4-IgE complex formation in patients with IgG4-RD was significantly higher than that in those without IgG4-RD (21.2% vs. 0%). No significant differences were observed between the groups in terms of clinical characteristics and laboratory data. However, the IgG4-IgE complex-positive group had a significantly higher frequency of pancreatic lesions (85.7% vs. 42.3%) and a significantly lower rate of retroperitoneal fiber/periarterial lesions (0% vs. 38.5%) than the IgG4-IgE complex-negative group. Conclusion The IgG4-IgE complex was found only in patients with IgG4-RD which may provide some clues to the pathogenesis and etiology of IgG4-RD.