摘要：

To establish the role of maternal -specific antibodies in the of hemorrhagic and caused by in infants, we examined sera from mothers of infants and toddlers with hemorrhagic or and mothers of infants with pyrexia of unknown origin. The mean titers of hemagglutination inhibition, neutralization, and -enhancing activities against were not statistically different among the three groups. However, among infants who developed hemorrhagic /there was a strong correlation between the mothers' 2 neutralizing titers and infant age at the time of onset of severe illness, where no such correlation was found among the other two groups. Furthermore, the actual age at which hemorrhagic /occurred in each infant correlated with the age at which maximum enhancing activity for 2 infection in mononuclear phagocytes was predicted. This critical time for the occurrence of hemorrhagic /was observed to be approximately 2 months after the time calculated for maternal 2 neutralizing antibodies to degrade below a protective level. In addition, sera of mothers of infants with hemorrhagic /enhanced to a slightly greater degree than did sera from mothers of infants with pyrexia of unknown origin and toddlers with hemorrhagic /. These data are consistent with the hypothesis that maternal antibodies play a dual role by first protecting and later increasing the risk of of hemorrhagic /in infants who become infected by .

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