Differences in Maternal Immunoglobulins within Mother's Own Breast Milk and Donor Breast Milk and across Digestion in Preterm Infants

Abstract

Maternal antibody transfer to the newborn provides essential support for the infant's naïve immune system. Preterm infants normally receive maternal antibodies through mother's own breast milk (MBM) or, when mothers are unable to provide all the milk required, donor breast milk (DBM). DBM is pasteurized and exposed to several freeze-thaw cycles, which could reduce intact antibody concentration and the antibody's resistance to digestion within the infant. Whether concentrations of antibodies in MBM and DBM differ and whether their survival across digestion in preterm infants differs remains unknown. Feed (MBM or DBM), gastric contents (MBM or DBM at 1-h post-ingestion) and stool samples (collected after a mix of MBM and DBM feeding) were collected from 20 preterm (26-36 weeks gestational age) mother-infant pairs at 8-9 and 21-22 days of postnatal age. Samples were analyzed via ELISA for the concentration of secretory IgA (SIgA), total IgA (SIgA/IgA), total IgM (SIgM/IgM) and IgG. Total IgA, SIgA, total IgM and IgG concentrations were 55.0%, 71.6%, 98.4% and 41.1% higher in MBM than in DBM, and were 49.8%, 32.7%, 73.9% and 39.7% higher in gastric contents when infants were fed with MBM than when infants were fed DBM, respectively. All maternal antibody isotypes present in breast milk were detected in the infant stools, of which IgA (not sIgA) was the most abundant.

Keywords: antibodies; breast milk; lactation; passive immunization; prematurity; proteolysis.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1

(A) pH values of milk and gastric contents at 1-h postprandial time from 20 preterm infants (26–36 weeks of gestational age (GA)) fed mother’s own breast milk (MBM) and donor breast milk (DBM). Values are mean ± SEM, n = 36 for each group (n = 20 for 8–9 days and n = 16 for 21–22 days of postnatal age). (B) Total protein concentration in milk and gastric contents from infant fed MBM and DBM at 8–9 days (n = 20) (C) Total protein concentration in milk and gastric contents from infant fed MBM and DBM at 21–22 days (n = 16). Asterisks show statistically significant differences between variables (*** p < 0.001; ** p < 0.01) using the Wilcoxon matched-pairs signed-rank test.

Figure 2

Immunoglobulin concentrations in milk and gastric contents at 1-h postprandial time from 20 preterm infants (26–36 weeks of gestational age (GA)) fed mother’s own breast milk (MBM) and donor breast milk (DBM). Concentration of (A) total IgA (SIgA/IgA), (B) secretory IgA (SIgA), (C) total IgM (SIgM/IgM) and (D) IgG in milk and gastric samples. Values are mean ± SEM, n = 36 for MBM and DBM (n = 20 for 8–9 days and n = 16 for 21–22 days of postnatal age). Asterisks show statistically significant differences between variables (*** p < 0.001; ** p < 0.01; * p < 0.05) using the Wilcoxon matched-pairs signed-rank test.

Figure 3

Proportion of total IgA, total IgM and IgG (A) in mother’s own breast milk (MBM), (B) in gastric contents at 1-h postprandial time from preterm infants fed MBM and (C) in infant stools (from MBM, DBM and/or infant self). Proportion of SIgA and IgA from total IgA (D) in mother’s own breast milk (MBM), (E) in gastric contents at 1-h postprandial time from preterm infants fed MBM and (F) in infant stools. Values are mean, n = 36 for MBM (n = 20 for 8–9 days and n = 16 for 21–22 days of postnatal age).