IgG4 immunoglobulin subclass and related pathological conditions or how to effectively imitate cancer disease.

Background: IgG4 is the least represented subclass of human imunnoglobulines G (IgG) in serum and differs from other antibodies by its unique bio-logical properties. Although its function in the immune response is not entirely clear, it is mainly involved in the regulation of the immune response. It is formed as a result of chronic or strong antigenic stimulation; in such a case, it becomes a predominantly formed IgG subclass.