Targeted immunoglobulin therapy for the prevention of neonatal infections

Premature infants demonstrate hypoglobulinemia and are at increased risk for serious infections. Although a cause-and-effect relation between low serum IgG levels and neonatal infections has not been established, prophylaxis of such severe infections may be possible by replacement of antibody with intravenous immunoglobulin (IVIG). For success, IVIG must provide specific antibodies to neonatal pathogens and reach therapeutic serum IgG target levels. Pilot investigations have demonstrated that IVIG reduces the incidence of bacterial sepsis among premature infants. Infants received IVIG every 2 weeks (or more frequently) until they weighed 2,000 g. Serum IgG levels were monitored after each dose so that the dose could be adjusted to achieve a target IgG level greater than 700 mg/dL. The observation that infection among placebo-treated patients occurred when the serum IgG level declined to less than 400 mg/dL suggests the importance of achieving a target level. In our preliminary analysis, the IVIG used did not reduce the incidence of infection with respiratory syncytial virus (RSV) and rotavirus or of necrotizing enterocolitis. That the lot of IVIG used did not contain significant antibody to RSV or rotavirus emphasizes the importance of pathogen-specific antibody. Because of the preliminary nature of these results and the potential for undetermined short-term and long-term sequelae, we do not recommend the indiscriminant use of IVIG for prevention or treatment of neonatal infections.