Induction of IgE antibody responses by protein allergens: inter-laboratory comparisons

There is a growing interest in the development of methods for the evaluation of the allergenic potential of novel proteins. One approach is the measurement of specific IgE antibody production stimulated by systemic (intraperitoneal; ip) exposure of BALB/c strain mice. In the current investigations, inter-laboratory comparisons have been performed of IgE antibody production induced in mice by food proteins of differing sensitizing potential. Female BALB/c strain mice (n=5) were exposed to 0.1% peanut agglutinin, an allergenic constituent of peanuts, to 2% ovalbumin (OVA), a major allergenic constituent of hensʹ egg, or to a protein considered to lack significant allergenicity, potato agglutinin (5%). Specific IgE antibody was measured by homologous passive cutaneous anaphylaxis assay and IgG and IgG1 antibody production was analysed by enzyme-linked immunosorbent assay (ELISA). Two independent experiments were conducted in each laboratory, but with all serological analyses conducted in one of the laboratories. Each of the proteins induced vigorous IgG and IgG1 antibody responses, with no statistically significant differences in titres recorded between laboratories. Furthermore, OVA and potato agglutinin induced responses of equivalent immunogenicity with respect to both IgG and IgG1 antibody titres. Administration of peanut agglutinin and OVA each stimulated marked IgE antibody responses in every experiment. In the two laboratories, titres ranged from 1:32 and 1:64 for peanut agglutinin, and from 1:8 and 1:32 for OVA. In contrast, exposure to potato agglutinin failed to induce vigorous IgE production, with no detectable IgE (negative with neat serum), or titres of 1 (positive with neat serum only) recorded. These data demonstrate that the induction of IgE antibody by food proteins of differing allergenic potential is a relatively robust phenomenon and transferable between laboratories. Furthermore, these results provide additional evidence that the measurement of antibody (IgE) responses in BALB/c mice may allow discrimination between allergens and those materials that apparently lack allergenicity.