BackgroundNewborns have limited specific immune capability at birth, owing to delayed and constrained development of adaptive immunity. To supplement this period the mother passively transfers antibodies to the child either transplacentally or through breast milk. When maternal alloimmunisation occurs through foreign or fetal red cell surface antigens, stimulating the production of immunoglobulin G (IgG) antibodies, these IgG antibodies can cross the placenta and cause haemolytic disease of the fetus and the newborn.ObjectiveWe present two case reports of a neonate and an infant in whom IgG red cell alloantibodies were transferred through maternal breast milk.MethodsMaternal serum, baby's serum and expressed breast milk samples were tested for the presence of red cell alloantibodies using gel card. Antibody screening, antibody identifications and titres alongside monospecific direct antiglobulin test, IgG subtypes were performed using the standard methods.ResultsIn the first case, a 6‐month‐old child was incidentally found to have positive antibody screen. Anti‐KELL1 was identified, which was also present in maternal serum and breast milk. The second neonate was evaluated for haemolysis and was found to have anti‐D. Anti‐D was also detected in the maternal serum and breast milk. Both babies did not have any sensitising events. The first baby was asymptomatic, but the second baby had ongoing haemolysis until 1 month.ConclusionWe report that maternal anti‐KELL1 and anti‐D antibodies were present in breast milk and were capable of being transferred to a feeding child. Our case report also raises interesting and unanswered immunologic fundamentals that should be considered in neonates with unexplained anaemia or delayed and persistent haemolysis.

Background and Objectives: Maternal antibodies are transferred to the child, predominantly IgG, via the transplacental route, and mostly IgA through breast milk.Cases reported by us and others have shown the transfer of red cell allo-antibodies through breast milk. This study was conducted to assess the presence of isohaemagglutinins in breast milk, the range of titres, and the correlation between breast milk and maternal plasma titres.Materials and Methods: A total of 176 mothers were recruited in this study. Breast milk was collected after sufficient feeding was established and within 2-5 days of delivery in a sterile container without any anticoagulant. Antibody screen, identification and titres were performed on maternal plasma as well as breast milk.Results: Anti-A and anti-B in breast milk corresponding to their respective maternal blood groups were found in all the samples. This study has shown titres in the breast milk of anti-A and anti-B ranging from 2 to 1024 in both saline and Coombs phases. There was no association between plasma and breast milk titres, thus making it impossible to predict which mother may potentially transfer a larger amount of these haemagglutinins. Isotypes of anti-A and anti-B were evaluated in both plasma and breast milk of 11 samples, which showed predominantly IgG in 7 (63.63%) and predominantly IgA in 4 (36.36%) samples. Conclusion:Our study demonstrates the presence of a wide range of titres for IgG antibodies of the ABO blood group system in breast milk. The clinical impact of this finding needs to be studied further, as it assumes great relevance in developing countries where anaemia continues to challenge young infants.

We appreciate the interest of Dr. Datta on our recently published article 'Breast milk contains red cell isohaemagglutinins: An observational study of 176 mothers' and for highlighting the many areas of research that could be pursued on this front.We wish, however, to clarify a few of the issues raised.With regard to the suggestion of using the tube technique as opposed to the column agglutination technology platform for testing