Improved IgG3 levels and reduced infection rate in a woman with CVID switched from intravenous to subcutaneous immunoglobulin therapy.

AIM: To report the interesting case of a patient with common variable immune deficiency disease who demonstrated varied responses to intravenous (IV) and subcutaneous (SC) immunoglobulin (Ig) therapy with regard to both infection frequencies and IgG3 subclass determinations. PATIENT & METHODS: As part of routine medical care, the author monitored total and IgG subclass levels, along with infection frequencies in a 35-year-old woman, with recurrent sinopulmonary infections diagnosed with common variable immune deficiency disease. RESULTS: During treatment with IVIg, the patient's annual rate of infections decreased, although she experienced severe headaches. After being switched to daily SCIg therapy, the headaches stopped, and her annual infection rate declined further. Her IgG3 levels, which were undetectable during IVIg therapy, increased substantially during SCIg treatment. CONCLUSION: The reason for the observed correlation between IgG3 level restoration and a decline in infection rate after being switched to SCIg therapy is not entirely clear. At the minimum, it may suggest that IgG3 levels may be a simple and useful surrogate marker to monitor Ig replacement sufficiency in certain patients.