Immunoglobulin-secreting cells of maternal origin can be detected in B cell-deficient mice

It is well known that the transfer of immunoglobulins (Igs) from mother to young via milk contributes to the offspring's immune defense. The present s tudy suggests that not only is IgG transmitted to progeny, but that functio nal maternal Ig-secreting cells (or B cells) can also be transferred to the neonate. We have used B cell-deficient (mu (-/-)) mice and found that a hi gh proportion of them obtain long-lasting, partial reconstitution of their serum Ig levels if born to mu (+/-) mothers. In some of these serum IgG-pos itive mu (-/-) mice, Ig-secreting cells were detected in spleen and bone ma rrow To ensure that cells of maternal origin were present in the progeny, m u (-/-) offspring born to mu (-/-) dams transgenic for green fluorescent pr otein (GFP) were used. In spleens and bone marrow from some of these mu (-/ -)GFP(-/-) offspring, GFP-positive cells were detected, which demonstrated that cells of maternal origin could infiltrate the progeny. In addition, sp lenic Ig-secreting cells were detected in mu (-/-) mice that were born to m u (-/-) dams and transferred to a lactating mu (+/+) foster dam at birth. T his indicates that maternal Ig-secreting cells can be transferred postnatal ly via milk.