IgG4-related disease: patient group characterization and rituximab therapy

Aim. To characterize a group of patients with IgG4-related disease (lgG4-RD) in a Russian population and to evaluate the efficiency of rituximab therapy. Subjects and methods. In 2009 to 2011, at the Research Institute of Rheumatology, Russian Academy of Medical Sciences, 30 patients (16 men and 14 women; mean age 44 years) were diagnosed with IgG4-RD that was confirmed by determination of serum IgG4 levels and immunohistochemical study of biopsy samples stained for IgG4-positive plasma cells. Seven patients received rituximab therapy. Results. It was assumed at baseline that there were different types of neoplasias in 12 (40%), non-Hodgkin's and Hodgkin's lymphomas in 10 (33.3%), Sjogren's syndrome in 5 (16.7%), and Wegener's granulomatosis in 3 (10%). When 2 or more locations were involved, the condition was regarded as multifocal fibrosclerosis (33.3%). Localized forms were revealed in 20 (66.7%) patients. Among them, the largest number of patients was those who had orbital pseudotumor, Mikulicz's disease, or retroperitoneal fibrosclerosis. The most common sites of involvement were orbits (66.7%), salivary glands (70%) and lymph nodes (36.7%). Comparison of serum IgG4 levels in 28 patients with IgG4-RD, 22 patients with Sjogren's disease, salivary and lacrimal gland lymphomas, and 10 healthy controls showed that the concentration of IgG4 was significantly higher in Group 1 (median 2.6 g/l; IQR 1.22-4.65 (p<0.001). Tissue IgG4/IgG ratio varied from 25 to 50% and averaged 38%. A moire-like pattern of varying fibrosis was noted in 83% of cases. Analysis of laboratory data revealed elevated C-reactive protein concentrations (46.7% with a mean of 39.5 mg/l; normal values <5.0 mg/l), increased erythrocyte sedimentation rate (60% with a mean of 37.6 mm/h), hypergammaglobulinemia (30% with a mean of 29.4%; normal range 13-22%), and rheumatoid factor (23.3%). After rituximab therapy, all the patients showed a decrease of IgG4 levels to the normal levels and positive changes evidenced by visualization techniques (computed tomography, magnetic resonance imaging). Conclusion. IgG4-RD is a novel problem in modern medicine, which requires a multidisciplinary approach and further study. Rituximab therapy is a promising treatment.