The influence of antigen dose on IgE production in different rat strains

Strain differences in total serum IgE levels and IgE antibody responses to various amounts of antigen were studied in rats. Five inbred strains (BN, Wistar R/A, DA, LEW, PVG), (Wistar R/A x BN)F1 and (LEW x BN) F1 hybrids were immunized twice at an interval of 28 days by intraperitoneal injection of 10 ng, 100 ng, 1 microgram, 10 microgram, 100 microgram or 1 mg ovalbumin and 1 mg A1(OH)3 in a volume of 0.5 ml. Total serum IgE and IgE antibody levels were followed. Both parameters were measured with a solid phase radioimmunoassay. A significant difference was observed in total IgE levels between the different strains. The IgE antibody response depended both on the strain and on the amount of antigen used for immunization. There was an optimal antigen dose for IgE antibody formation, differing from strain to strain. F1 hybrids had total IgE levels and IgE responses intermediary between those of the two parent strains. A good correlation existed between the total serum IgE level before immunization and the magnitude of the optimum IgE antibody responses in the different strains. These results suggest that there may be a genetic influence on both parameters, the total IgE level and the specific IgE antibody response. The IgE antibody response is also dependent on the dose of antigen.