Maternal IgA: Matchmaking in Early Childhood

Maternal and neonatal IgG against Klebsiella pneumoniae are associated with broad protection from neonatal sepsis: a case-control study of hospitalized neonates in Botswana

Sepsis is the leading postnatal cause of neonatal mortality worldwide. Globally Klebsiella pneumoniae is the leading cause of sepsis in hospitalized neonates. This study reports development and evaluation of ELISA for anti-Klebsiella IgG using dried blood spot samples and evaluates the association of anti-Klebsiella IgG (anti-Kleb IgG) antibodies in maternal and neonatal samples and the risk of neonatal sepsis. Neonates and their mothers were enrolled at 0-96 hours of life in the neonatal unit of a tertiary referral hospital in Gaborone, Botswana and followed until death or discharge to assess for episodes of blood culture-confirmed neonatal sepsis. Neonates with sepsis had significantly lower levels of Kleb-IgG compared to neonates who did not develop sepsis (Mann-Whitney U, p=0.012). Similarly, samples from mothers of neonates who developed sepsis tended to have less Kleb-IgG compared to mothers of controls (p=0.06). The inverse correlation between Kleb-IgG levels and all-cause bacteremia suggests that maternal Kleb-IgG is broadly protective through cross-reactivity with common bacterial epitopes. These data support the continued use of immunoglobulin assays using DBS samples to explore the role of passive immunity on neonatal sepsis risk and reaffirm the critical need for research supporting the development of maternal vaccines for neonatal sepsis.

[Effect of pasteurization and freezing on the content of IgA1 and IgA2 subtypes in breast milk]

OBJECTIVE

To determine the effect of pasteurization and freezing on the content of IgA1 and IgA2 in breast milk.

METHODS

Observational, retrospective study, carried out in women who had been breastfeeding their newborn for more than 30 days, and could donate 50 mL of milk. The concentration of IgA1 and IgA2 was determined by turbidimetry, before and after being subjected to pasteurization and freezing, every 15 days for 2 months. Freezing was at -20°C. A total IgA content of 1598.5 mg/dL was found.

RESULTS

10 breast milk donors were selected. The initial concentration of IgA1 and IA2 was 651 and 945.7 mg/dL, respectively; At the end of the freezing times, the content of both immunoglobulins decreased: IgA1 of 74% and IgA2 of 86%. After the treatments, the immunoglobulin content decreased dramatically, with a significant difference of p < 0.05.

CONCLUSIONS

Pasteurization and freezing significantly affect the content of IgA1 and IgA in breast milk; therefore, breast-feeding remains the best way to offer full immunological protection to the infant.

Secretory immunoglobulin A in preterm infants: determination of normal values in breast milk and stool

BACKGROUND

IgA and its secretory form sIgA impact protection from infection and necrotising enterocolitis but little is known about quantities in preterm mums own milk (MOM) or infant stool, onset of endogenous production in the preterm gut, and what affects these.

METHODS

We measured by ELISA in MOM and stool from healthy preterm infants total IgA and sIgA longitudinally and additionally in MOM fresh, refrigerated, frozen, and after traversing feeding systems.

RESULTS

In 42 MOM (median gestation 26 weeks), we showed total IgA levels and sIgA were highest in colostrum, fell over 3 weeks, and were not impacted by gestation. Median IgA values matched previous term studies (700 mcg/ml). In MOM recipients stool IgA was detected in the first week, at around 30% of MOM quantities. Formula fed infants did not have detectable stool IgA until the third week. Levels of IgA and sIgA were approximately halved by handling processes.

CONCLUSIONS

MOM in the 3 weeks after preterm delivery contains the highest concentrations of IgA and sIgA. Endogenous production after preterm birth occurs from the 3 week meaning preterm infants are dependent on MOM for IgA which should be optimised. Routine NICU practices halve the amount available to the infant.

IMPACT

(Secretory) Immunoglobulin A (IgA) is present in colostrum of maternal milk from infants as preterm as 23-24 weeks gestational age, falling over the first 3 weeks to steady levels similar to term. Gestation at birth does not impact (secretory) IgA levels in breast milk. IgA is present in very preterm infant stools from maternal milk fed infants from the first week of life, but not in formula milk fed preterm infants until week three, suggesting endogenous production from this point. Refrigeration, freezing, and feeding via plastic tubing approximately halved the amount of IgA available.