The impact of lipid-based nutrient supplementation on anti-malarial antibodies in pregnant women in a randomized controlled trial

Abstract

Background: Malaria and undernutrition frequently coexist, especially in pregnant women and young children. Nutrient supplementation of these vulnerable groups might reduce their susceptibility to malaria by improving immunity.

Methods: Antibody immunity to antigens expressed by a placental-binding parasite isolate, a non-placental binding parasite isolate, merozoites and schizonts at enrolment (before 20 gestation weeks) and at 36 gestation weeks were measured in 1,009 Malawian pregnant women receiving a daily lipid-based nutrient supplement, multiple micronutrients or iron and folic acid, who were participants in a randomized clinical trial assessing the effects of nutrient supplementation on pregnancy outcomes and child development (registration ID: NCT01239693).

Results: Antibodies to placental-binding isolates significantly increased while antibodies to most merozoite antigens declined over pregnancy. Overall, after adjustment for covariates, the type of supplementation did not influence antibody levels at 36 gestation weeks or the rate of change in antibody levels from enrolment to 36 weeks. A negative association between maternal body mass index and opsonizing antibodies to placental-binding antigens (coefficient (95% CI) -1.04 (-1.84, -0.24), was observed. Similarly, women with higher socioeconomic status had significantly lower IgG and opsonizing antibodies to placental-binding antigens. Neither of these associations was significantly influenced by the supplementation type.

Conclusions: In the current cohort nutrient supplementation did not affect anti-malarial antibody responses, but poor and undernourished mothers should be a priority group in future trials.

Figure 1

Antibodies to malaria antigens at enrolment and at 36 gestation weeks. (A) Antibodies to variant surface antigens expressed by placental-binding and non-placental-binding parasite isolates. (B) Antibodies to merozoite antigens and schizont extract. Data presented as box plots with the Y axis representing antibody levels as a percentage of the positive control. The whiskers denote the 10^th and the 90^th percentiles with outliers. Wilcoxon matched pairs test performed for antibody comparisons between enrolment and 36 gestation weeks. N = 1,009.

Figure 2

Antibodies to malaria antigens at 36 weeks categorized by supplementation type. (A) Antibodies to variant surface antigens expressed by placental-binding and non-placental-binding parasite isolates. (B) Antibodies to merozoite antigens and schizont extract. Data presented as box plots with the Y axis representing antibodies as a percentage of the positive control. The whiskers denote the 10^th and the 90^th percentiles with outliers. Mann Whitney U test performed for antibody comparisons between supplementation groups LNS versus IFA and LNS versus MMN. N = 1,009.

Figure 3

Antibodies at 36 weeks stratified by maternal body mass index and socioeconomic status. (A-C) Antibodies to variant surface antigens of placental-binding and non-placental-binding parasite isolates stratified by body mass index (BMI) groups and supplementation groups, (D-F) stratified by socioeconomic status (SES) and supplementation groups. BMI groups < 18.5 kg/m², n = 57; 18.5-25 kg/m², n = 822; >25 kg/m², n = 122. High SES  = 441 and low SES n = 560.