Antibodies that inhibit Plasmodium falciparum adhesion to chondroitin sulfate A are associated with increased birth weight and the gestational age of newborns

Abstract

Antibodies that inhibit Plasmodium falciparum adhesion to the placental receptor chondroitin sulfate A are associated with a reduced risk of placental malaria, but whether these antibodies lead to improved pregnancy outcomes is unknown. We measured antiadhesion antibody levels in parturient women in western Kenya, where malaria transmission is intense. Secundigravid women with antiadhesion activity in their plasma delivered babies that were on average 398 g heavier (P = 0.019) and 2 weeks more mature (P = 0.002) than babies delivered to secundigravidas without antiadhesion activity. Our findings support the development of antiadhesion vaccines to prevent poor fetal outcomes due to pregnancy malaria.

FIG. 1.

Antiadhesion antibodies in placental plasma samples from parturients of different gravidities. Antibodies were quantified as the number of IEs binding to CSA while in the presence of maternal plasma and expressed as percentage of binding in the presence of control, nonimmune plasma. Decreasing numbers of bound IEs indicate increasing levels of antiadhesion antibodies. Antiadhesion activity was defined as present or protective when plasma inhibited binding to a level below 35% of control plasma (indicated by the dashed line), as in previous studies (3). Box plots indicate medians (center lines), 75th percentiles (boxes), and 90th percentiles (bars). The remaining values are individually plotted as circles.

FIG. 2.

Scattergram of infant birth weight and maternal plasma antiadhesion activity measured in secundigravid women. Plasma samples that reduced IE binding to CSA were associated with increased birth weight. The regression line is indicated.

FIG. 3.

Relationship between antiadhesion activity and gestational age of infants born to secundigravid women. Shown is a frequency distribution of gestational ages of infants born to women with (A) or without (B) plasma antiadhesion activity. Plasma that reduced parasite binding to a level below 35% of control binding was considered to have antiadhesion activity.