Pathogenicity of IgG in patients with IgG4-related disease

OBJECTIVE

IgG4-related disease (IgG4-RD) is a systemic disease characterised by elevated serum IgG4 and IgG4-positive lymphoplasmacytic infiltration in the affected tissues. The pathogenic role of IgGs, including IgG4, in patients with IgG4-RD, however, is unknown.

DESIGN

We examined the pathogenic activity of circulating IgGs in patients with IgG4-RD by injecting their IgGs into neonatal male Balb/c mice. Binding of patient IgGs to pancreatic tissue was also analysed in an ex vivo mouse organ culture model and in tissue samples from patients with autoimmune pancreatitis (AIP).

RESULTS

Subcutaneous injection of patient IgG, but not control IgG, resulted in pancreatic and salivary gland injuries. Pancreatic injury was also induced by injecting patient IgG1 or IgG4, with more destructive changes induced by IgG1 than by IgG4. The potent pathogenic activity of patient IgG1 was significantly inhibited by simultaneous injection of patient IgG4. Binding of patient IgG, especially IgG1 and IgG4, to pancreatic tissue was confirmed in both the mouse model and AIP tissue samples.

CONCLUSIONS

IgG1 and IgG4 from patients with IgG4-RD have pathogenic activities through binding affected tissues in neonatal mice.

Japanese consensus guidelines for management of autoimmune pancreatitis: I. Concept and diagnosis of autoimmune pancreatitis

As the number of patients with autoimmune pancreatitis (AIP) is increasing in Japan, practical guidelines for managing AIP need to be established. Three committees [the professional committee for developing clinical questions (CQs) and statements by Japanese specialists, the expert panelist committee for rating statements by the modified Delphi method, and the evaluating committee of moderators] were organized. Fifteen AIP specialists extracted specific clinical statements from a total of 871 articles in the literature using a PubMed search (1963-2008) and a secondary database, and developed the CQs and statements. The expert panelists individually rated these clinical statements using a modified Delphi approach in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid. The professional committee developed 13, 6, 6, and 11 CQs and statements for the concept and diagnosis, extra-pancreatic lesions, differential diagnosis and treatment, respectively. The expert panelists regarded them as valid after two-round modified Delphi approaches.After evaluation by the moderators, the Japanese clinical guidelines for AIP were established. The digest versions of the present guidelines have been published in the official journal of the Japan Pancreas Society, "Pancreas." Full versions divided into three series are scheduled to be published in the present and followings two issues in the Journal of Gastroenterology with approval of Professor Go VLW, the Editor-in-Chief of "Pancreas."