Measles‐Virus–Neutralizing Antibodies in Intravenous Immunoglobulins

Measles infection induces lifelong immunity; however, wild-type infection stimulates higher levels of measles-virus-neutralizing antibodies (mnAbs) than does vaccination. Because the proportion of the donor population with vaccine-induced measles immunity is increasing, this study was conducted to determine whether this shift in demographic characteristics affects mnAb levels in contemporary lots of Immune Globulin Intravenous (Human) (IGIV). When 166 lots of 7 IGIV products manufactured between 1998 and 2003 were assayed by plaque-reduction neutralization test, there was a progressive decrease in geometric mean titers in lots manufactured between 1999 and 2002. IGIV products manufactured from recovered plasma had significantly higher titers than did those manufactured from Source Plasma, which could reflect a change in donor demographic characteristics, because Source Plasma donors tend to be much younger. A reduction in mnAbs also correlated with the loss of either IgG1 and IgG3, possibly because of certain manufacturing procedures, or bivalent antibodies (i.e., intact IgG and F(ab')2), because of fragmentation.