Transmission of antimalarial immunity (Plasmodium berghei) from mother rats to their young during lactation

Abstract
(1) This work confirms the report of Bruce-Chwatt (1954), that suckling rats, born of mothers which have been immunized against Plasmodium berghei, show a slight but definite resistance to infection with this parasite. The resistance increased during the nursing period but it was of a temporary nature, and 7 weeks after weaning it had disappeared entirely. (2) Experiments, in which the litters of immune and normal animals were exchanged soon after birth, showed that transference of resistance occurred mainly, if not entirely in the milk.The effect of immune milk could be duplicated in normal suckling rats by giving them immune serum by mouth.Rats which had reached the age of 22 days when first given serum showed no resistance ; evidently malarial antibodies can no longer be absorbed through the gut at this age. (3) The transitory resistance to malarial infection shown by human infants, living in hyper-endemic areas, may be due in part to a similar transference of maternal antibodies; in this case, however, the antibodies are probably transferrred in utero and not in the milk.