In this study, we found that anti-β-glucan IgG antibodies were present in sera from the peripheral blood (PB) of normal adult donors and the umbilical cord blood (UCB) of neonates using a novel enzyme-linked immunoassay (EIA) developed in our laboratories. The titers of anti-β-glucan IgG antibodies from the PB of normal adult donors were significantly (P < 0.05) higher than those from the UCB of neonates. These findings suggest that anti-β-glucan IgG antibodies in sera from the UCB of neonates may be transferred from the mothers to the neonates via the placenta. The reactivity of serially diluted purified IgG antibody prepared from the serum of a normal adult donor (human purified IgG antibody) was also positive against β-glucan in a dose-dependent manner. On the other hand, a standard rabbit anti-β-glucan IgG antibody completely blocked the reactivity of human purified IgG antibody to β-glucan in a dose-dependent manner. Taken together, these findings show that human sera contain specific anti-β-glucan IgG antibodies and suggest that these anti-β-glucan IgG antibodies may have unique actions in various immunological responses
