In Reply.—A normal newborn infant is generally expected to have a rubella HI antibody titer comparable to that of its mother due to placental passage of maternal IgG antibodies. Dr Buchta's case demonstrates a well-recognized phenomenon observed in mature or postmature infants. These infants may be born with levels of IgG that are substantially higher than those of their mothers.1.2 The precise causes of this concentration of antibody proteins in the infant circulation have not been established. Such placental concentration of antibody protein can result in the newborn rubella titer being twofold to fourfold higher than the corresponding maternal titer. Such elevations of rubella titers in these infants may occasionally raise the suspicion of congenital infection. The lack of persistence of the rubella HI antibody titer in Buchta's case, with the documented decrease in titer following the expected 30-day half-life of maternal IgG, however, supports his conclusion that
BIANO S, HERRMANN KL. Congenital Rubella-Reply. Am J Dis Child. 1976;130(9):1037. doi:10.1001/archpedi.1976.02120100126028
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