| Litters fed from Rag -/-
mothers, who have very few circulating or milk lymphocytes,
made lower levels of antibody when compared with those fed
from Rag +/+ mothers. Those with Rag +/- mothers showed
similar responses to Rag +/+ pups. By exchanging mothers, the
antibody responses in the pups could be altered. This
observation suggests that milk lymphocytes are indeed a
significant component to the neonatal murine immune system. It
is not clear whether it is the lymphocytes themselves, or
factors they produce, which are necessary, or at which
cellular or molecular level the mechanism operates for this
adjuvant-like activity. The observation may well link with
that made in babies who have been shown to have significantly
larger thymus glands if breast-fed. The Rag mouse model
allows other questions to be asked of milk production, the
development of mastitis, and therefore milk quality and
quantity. Such questions are important in agricultural
situations where inflammatory changes are well known to reduce
the milk output of domesticated animals. The term 'Rag' is
relevant here, not as an eponym for 'Rapid activating gene'
but as part of a name, 'Round Oak Rag Apple Elevation', a
Holstein cow, had triplets, 26 sisters and 4215 three quarter
sisters as a consequence of assisted reproductive technology (VanRaden
(1997) J Dairy Sci 75). The lactation records of all
these animals have been followed for three generations. This
extensive database is beginning to allow careful genetic
analysis of milk immunology; it too demonstrates the
significance of maternal genetic factors to milk quality and
the outcome of the calf consuming that milk.
Such data give a prospect to augmenting existing milks.
Might milks be adjusted for the premature so as to enhance
antibody responses in those whose trans-placental antibody
levels are low? Might these factors allow improvement of the
routine vaccination programmes, designed around the poor
antibody responses of the infant human? Such prospects offer
advantages to those working locally in neonatal nurseries or
on a wider scale in public health.
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