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Fig. 4 | Pediatric Rheumatology

Fig. 4

From: IgG4-related disease: a systematic review of this unrecognized disease in pediatrics

Fig. 4

Proposed mechanism of the formation of IgG4 antibodies by ‘’Fab-Arm” exchange. IgG4 antibodies continuously exchange half molecules with other antibodies making them bivalent reactive antibodies with two different antigen-binding fragments. These antibodies are also unable to activate the classical complement system and can bind to antigens. However, as a result of bivalent reactivity unable to form immune complexes. Because of these characteristics the IgG4 antibodies are most probably anti-inflammatory agents rather than pro-inflammatory. Fab = antigen binding fragment

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