Impact of IVIG therapy on serologic testing for infectious diseases.

Intravenous immunoglobulin (IVIG) is used to treat an increasing number of conditions. The anti-inflammatory and immunomodulatory effects of IVIG can be life-saving; however, recent administration may complicate evaluation for infection. To assess the impact of IVIG therapy on a variety of common viral, bacterial, fungal, and parasitic serologies we prospectively evaluated serologic changes pre- and post-IVIG infusion in 7 participants. The number of new antibody detections ranging from 2 to 5. New detections included positivity for Epstein-Barr virus early D antigen, herpes simplex virus, West Nile virus, cytomegalovirus, and the endemic mycoses Histoplasma and Coccidioides. The greatest number of newly positive serologies was observed in subjects receiving cumulative doses of IVIG in excess of 100 g. Our results illustrate the difficulty in serologic interpretation following IVIG therapy and suggest a dose-response to new positive results. These findings may be a helpful resource to clinicians facing similar circumstances.