Both maternal and newborn IgMs inhibit influenza virus-induced hemagglutination in vitro

Abstract

Most serum immunoglobulins M (IgMs) are “natural IgMs”, which are produced apparently spontaneously without exogenous antigenic or microbial stimuli. The IgMs are the first immunoglobulins expressed in the human fetus, and the maternal IgM do not cross the placenta in the normal conditions. We currently lack a clear understanding of the molecular basis for immunological differences or identities of IgM repertoires between adults and neonates, so we have tried to apply a simple and illustrative method to compare the properties of such IgM antibodies. This study was undertaken to compare the abilities of pairs of maternal and newborn highly-purified total serum IgM antibodies to block influenza virus agglutinins. We collected ten pairs of serum samples from cord blood of apparently healthy newborns and venous blood of their mothers. The highly purified total IgM antibodies were obtained by sequential salt fractionation and affinity chromatography. The effect of IgM antibodies on virus hemagglutinin interaction with erythrocytes was evaluated by hemagglutination reaction using influenza virus vaccine. According to the titer of influenza hemagglutinins, the IgM antibodies of newborns decreased hemagglutination of erythrocytes two to four times more efficiently compared to IgM antibodies of their mothers (8 out of 10 cases). Our results demonstrate that serum IgMs of newborns are able to interfere with influenza virus agglutinins even more efficiently than those of adults. These data may be useful for better understanding of immune system development in newborns.

Keywords

• cord blood serum
• hemagglutination inhibition assay
• immunoglobulin m (igm)
• mother venous serum