Research in Medicine

Abstract

Background: In the serum of healthy people, IgG4 has lowest concentration among the different sub-classes of IgG. Elevation of serum IgG4 in response to chronic antigenic stimulation and inflammation has been reported. Inflammation, histopathologic lesions and systemic organ involvement have been reported in the IgG4-related disease (IgG4-RD). In this article we review IgG4 unique features and its role in immunopathogenesis of IgG4RD; new class of human disease. Also we discuss the IgG4 roles and its therapeutic potential in tumor.

Method: We systematically searched the Pub Med, Google Scholar, Scopus and Science Direct databases with IgG4, IgG4 related disease and IgG4-RD key words .Finally, Seventy four English language articles reporting IgG4 and IgG4 RD were included.

Conclusion and Recommendations: IgG4-RD is classified as rare diseases and to date exact prevalence of it has not been reported. In recent years the disease features have been described, but a long way is ahead of scientists to understand of IgG4RD mechanisms. The role of humoral (antibody) immune response against tumor antigens is the main interest of scientists. Histological studies in some tumors such as melanoma show the presence of anti-tumor antibodies within inflammatory tumor lesions.  Unique biological property of IgG4, such as the ability to switch Fab arms, results in inhibition of immune complex formation and ineffective antibody dependent cell killing.IgG4 as blocking antibody has protective role in allergy by inhibiting the release of mast cells granules. Also in malignant melanoma, IgG4 suppresses antitumor immune response via inhibition of IgG1 binding to tumor cells. These finding emphasis that, new investigations are necessary for understanding the importance of IgG4 in health and diseases.