Immunoregulation of IgE responses: the role of the gut in perspective.

In adult rats and mice of most strains the experience of antigen whether by mouth or by injection usually leads to a diminished rather than a heightened IgE response to a subsequent exposure. This is because these animals have a highly developed capacity to suppress the production of IgE by immunoregulatory mechanisms which can be activated by the administration of even minute quantities of antigen. The situation in young animals is less clear but there are indications that the suppressive mechanisms are less well developed. However, recent experiments in rats have shown that a relatively long lasting suppression of IgE responsiveness occurs in the offspring of immunized mothers and that this effect is mediated by maternal IgG. In this way, the influence of the immunized mother can be seen to compensate for any deficiencies of the developing immunoregulatory mechanisms of the young animal. These experiments were designed to explore ideas about the physiological regulation of IgE responses.