ORAL TOLERANCE INDUCED TO HOUSE-DUST MITE EXTRACT IN NAIVE AND SENSITIZED MICE - EVALUATION OF IMMUNOGLOBULIN-G ANTIIMMUNOGLOBULIN-E AUTOANTIBODIES AND IGG-IGE COMPLEXES

We investigated the effect on specific antibody response of naive and sensitized mice orally administrated with low (0.25 mg) or high (10.0 mg) doses of Dermatophagoides pteronyssinus (Dp) extract. We also exam ined the effect of oral administration of Dp on the production of auto antibodies to immunoglobulin G (IgC) and immunoglobulin E (IEE). Naive and sensitized mice both showed a marked down-regulation of IEE antib ody production, regardless of the dose of DF We also detected an inhib itory effect of the total ISE levels and the allergen-specific IgG1, I gG2a and IgG2b antibody response in sensitized mice given the low dose of Dp. In contrast, high doses of Dp stimulated IgG1 antibody product ion in both naive and sensitized animals. In addition, the oral tolera nce induction protocol stimulated anti-F(ab')(2 gamma) and anti-Fc gam ma autoantibody production. Evaluation of Ige anti-IgE autoantibodies by a direct enzyme immunoassay (EIA) revealed the presence of these au toantibodies, predominantly of the IgG1 isotype, specifically in those animals fed with the high dose. In contrast, IgG-IgE complexes, deter mined by EIA using immobilized anti-IgE antibodies, were detected main ly in sera of control animals. The autoantibody anti-IgE specificity w as tested against IgE-TNP and IgE-DANSYL murine proteins and revealed different inhibition profiles, suggesting the action of heterogeneous subpopulations of autoantibodies. Taken together, our results show tha t the oral tolerance protocol with Dp was able to modulate the product ion of allergen-specific IgE antibodies in both naive and sensitized a nimals. In addition, we suggest that anti-IgE autoantibodies participa te in the modulation of allergic response triggered by oral tolerance protocols.