The mother-offspring dyad and the immune system

A. The mother and the fetus. The mother's immune system reacts against the fetus and there is therefore a risk of destruction of or damage to the fetus. We are now beginning to understand some of the mechanisms that protect the fetus, but, when these are defective, intrauterine growth retardation or abortions may ensue. However, the cytokines of this maternal immune response to the fetus also monitor different phases of pregnancy, starting with effects on the ovarium and involving preparation of the decidua for the implantation of the fertilized egg, the growth of the trophoblasts, the production of hormones important for the pregnancy and finally of the prostaglandins that induce delivery. B. The mother and the child. Human milk contains anti-idiotypic antibodies which after transfer to the offspring are capable of enhancing antibody responses. Human milk contains numerous leucocytes especially during early lactation. There is increasing evidence that milk lymphocytes are taken up by the breastfed infant, which seems to have become tolerant to maternal HLA. Breastfeeding mothers are therefore good donors of renal transplants to their breastfed offspring in adult age, too.

It is suggested that the milk lymphocytes may be taken up by the offspring and that immunological information is thereby carried over from the mother. This mechanism may explain why breastfeeding seems to confer enhanced protection against infections also some years after the termination of breastfeeding.