IgG asymmetric anti-ovalbumin antibodies synthesized by virgin and pregnant rats

A study on the synthesis of asymmetrical IgG molecules 'with no specific activity' and with anti-ovalbumin activity was carried out both in virgin rats and in rats inoculated with ovalbumin and made pregnant by syngeneic and allogeneic males. Before pregnancy, female rats synthesize about 23% of asymmetrical IgG molecules, when the level of these molecules is assessed in total IgG, in anti-ovalbumin IgG and in the supernatant from the adsorption of anti-ovalbumin antibodies. On the other hand, anti-ovalbumin antibodies isolated are predominantly of the symmetrical IgG type; they are also precipitants and effectors of the biological mechanisms that the host operates to preserve pathogenic antigens (bacteria, parasites). In rats pregnant by syngeneic and allogeneic males, the ratio asymmetric/symmetric IgG molecules increases, and the anti-ovalbumin antibodies are mainly of the asymmetrical IgG type, which aid antigen-blocking. Similar results are found in virgin rats, immunized with ovalbumin and intraperitoneally transferred simultaneously with supernatants of placental cultures. These results suggest that, during pregnancy, there is an increase of the IgG asymmetric/symmetric molecule ratio, produced by placental factors, whatever the immunogen specificity may be. Speculations about this fact are presented.