Symptomatic IgG3 deficiency successfully treated with intravenous immunoglobulin therapy.

We report the case of a 35 year old female who presented with an 8 year history of repeated upper respiratory tract infection, lymphadenopathy and sinusitis associated with IgG3 deficiency. Courses of monthly intravenous immunoglobulin therapy (0.4 g/kg) resulted in a dramatic clinical improvement on three different occasions. We suggest that investigation of adults with features of immunosuppression, despite normal levels of total IgG, should include IgG3 subclass analysis and that symptomatic patients should be given a trial of immunoglobulin replacement therapy.