Cross-reactive neutralizing antibody against pandemic 2009 H1N1 influenza a virus in intravenous immunoglobulin preparations.

Prepandemic intravenous immunoglobulin (IVIG) and sera from Kawasaki disease patients treated with this IVIG were analyzed for 2009 H1N1-specific microneutralization and hemagglutination inhibition antibodies. All 6 different IVIG preparations tested had significant levels of cross-reactive-specific antibody at a concentration of 2.0 g/dL of immunoglobulin. Sera from 18 of 19 Kawasaki disease patients had significant increases of cross-reactive-specific antibody after 2.0 g/kg of prepandemic IVIG. These results suggest a role for adjunctive IVIG therapy for severe and/or drug-resistant 2009 H1N1 virus and other highly antigenically drifted influenza strains, particularly in the immunocompromised.