Children and Adults with PFAPA Syndrome: Similarities and Divergences in a Real-Life Clinical Setting.

Introduction: Analogies or differences of periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome in children and adults are barely known. The aim of our study was to compare the overall characteristics of a large cohort of patients, both children and adults, diagnosed with PFAPA syndrome.

Methods: In the last decade, we identified 120 children and 63 adults with periodically recurring fevers, who fulfilled the criteria for PFAPA diagnosis.

Immunological Role of IgG Subclasses.

The loss of tolerance to self-antigens is the unequivocal "red line" of autoimmunity: both development of autoreactive T and B cells and production of polyclonal autoantibodies represent seminal keys to the pathogenesis of protean autoimmune diseases. Most of these autoantibodies are immunoglobulins G (IgG), functionally distinguished in four subclasses named IgG1, IgG2, IgG3, and IgG4, due to structural differences in the hinge and heavy chain constant regions. Different studies analyzed serum levels of IgG subclasses in the course of different disorders, showing that they might have a pathogenic role by regulating interactions among immunoglobulins, Fc-gamma receptors, and complement.