The development of IgE-suppressive immunocompetence in young animals: influence of exposure to antigen in the presence or absence of maternal immunity.

Previous studies recognized a prolonged suppression of egg-albumin (EA)-specific IgE responsiveness in the progeny of immunized female rats, and showed that an identical effect was produced by the administration of small amounts of specific IgG during the first few days of life. Both manipulations also elevated the primary IgG response to a subsequent immunization but with less consistency. We have now investigated the effects on the progeny of varying the type of maternal response by immunizing with antigen given with or without adjuvant. Mothers immunized with EA without adjuvant (by mouth or parenterally) in whom both IgE and IgG responses are thereby suppressed do not influence the antibody-responsiveness of their progeny. By contrast, mothers immunized with EA in adjuvant, a procedure which suppresses IgE but enhances IgG responsiveness to the antigen, transfer both effects to their offspring. In this way, both IgE-suppression and IgG-enhancement are seen to correlate with the transmission of maternal IgG. EA administered either by mouth or parenterally in the period up to 6 weeks after birth, suppresses both IgE and IgG responses to subsequent specific challenges in a dose-dependent manner. The results of feeding antigen to the progeny of (IgG-transmitting) immune mothers indicated that passive and active immunity in the young rat, although both suppressing IgE-responsiveness, do not have additive depressive effects.