Antibodies given orally in the neonatal period can affect the immune response for two generations: Evidence for active maternal influence on the newborn's immune system

Two day old Wistar rats were tube fed with 1 or 10 mu g of a mouse IgG1 mon oclonal anti-idiotypic (a-Id) antibody that was directed against an anti-Es cherichia coli-K13 capsular polysaccharide antibody. A control group was gi ven 10 mu g of an unrelated control antibody. Six weeks after the administr ation of antibodies, the rats were intestinally colonised with an ovalbumin (OVA)-producing E. coli O6K13 strain. At 8 weeks of age, the male rats (fi rst generation) and the offsprings of the female rats (second generation), were parenterally immunised with OVA and dead wild type E. coli O6K13, and the immune response was followed. In the rats of the first generation, ther e were no major differences between the groups in the immune response to th e bacterium. However, the offspring of the neonatally a-Id administered rat s had a profoundly affected immune response to the idiotypically connected antigen K13, but also to other antigens on the bacteria. Thus, a-Id treatme nt in the first generation gave, in the second generation, a greatly enhanc ed serum antibody response to the spatially related antigens OVA and O6 LPS , as well as to the idiotypically connected antigen K13. Concurrently, the in vitro spleen cell proliferative response to both OVA and the wild type b acterium was lowered. Overall, greater effects were seen with the higher do se of a-Id. In conclusion, our results demonstrate that by giving monoclona l antibodies idiotypically connected to a single bacterial component to neo natal rats, one profoundly influence the immune response also to other-spat ially related-bacterial antigens in their offsprings.