Transplacental Transfer of Total Immunoglobulin G and Antibodies to Plasmodium falciparum Antigens between the 24th Week of Gestation and Term

Abstract

Full-term newborns have antibody (Ab) repertoires and levels similar to their mothers to help protect them from environmental pathogens. Unfortunately, preterm babies, especially those born < 34 weeks, have reduced levels of protective antibodies. In Africa, antibodies to Plasmodium falciparum are important in protection from malaria. This study investigated the transfer of total IgG and antibodies to 9 P. falciparum antigens and tetanus toxoid between 24 weeks and term. Paired maternal and cord samples from 166 preterm (24–37 weeks) and 154 term deliveries were used. Transfer efficiency was expressed as the ratio of Ab levels in cord to maternal plasma (CMR). At 24–25 weeks, CMR ranged from 0.31 to 0.94 for the different antigens; the rate of transfer was similar for all antigens between 24–40 weeks; resulting in median CMR of 0.49 to 0.95 at term. Babies of mothers with hypergammaglobulinemia and normal IgG levels had similar amounts of IgG, supporting data that saturation of the neonatal Fc-receptor occurs at ~ 16 mg IgG/ml. Thus, babies born prior to 34–35 weeks in Africa are likely to have reduced Ab levels to some, but not all antigens. Since IgG transfer is Fc-mediated, why differences exist in CMR among the antigens warrants further investigation.