Neonatal ingestion of IgG-containing milk increases the survival of adoptively transferred B-lineage cells in B cell-deficient mice.

This study shows that neonatal ingestion of immunoglobulin-containing milk increases the survival of adoptively transferred B-lineage cells in non-irradiated B cell-deficient (mu-/-) mice. Neonatal mu-/- mice were either transferred to lactating mu+/+ foster dams, allowing them to suckle IgG-containing milk, or were kept with their mu-) dams, without IgG in the milk. After adoptive transfer of spleen cells as adults, serum-IgG levels, numbers of plasma cells, T and B cells in spleen and bone marrow were determined. The results showed that the mice which had received milk-IgG had significantly higher levels of serum-IgG and splenic B cells, as well as a higher number of Ig-secreting cells in spleen and bone marrow. This indicates that the mice might have been tolerised against IgG as neonates, if allowed to ingest Ig-containing milk. There is, however, a possibility that B cells in the milk may also contribute to the observed tolerising effect. In summary, the results suggest that 'cross-fostering' could be a suitable method to facilitate the long-term reconstitution of B- and plasma cell numbers in non-irradiated B cell-deficient mice.