Treatment with conjugates of polysarcosine and grass pollen allergen extracts efficiently suppressed the induction of IgE responses in mice. The suppressive activity was shown to be allergen-specific and required covalent linking of the polysarcosine. Inhibitory effects could be overcome by booster injections of native allergen when these were given 3–4 weeks after treatment with conjugates. Administration of conjugates had only marginal effects on established IgE responses. The variance of these results with those of other studies on IgE suppression and the suitability of murine models for investigating reaginic antibody suppression are discussed.

The effects have been studied of three different chemical modifications of timothy grass pollen extract on various immunological properties. The ability to induce IgG antibody with specificity for native antigen was least affected by glutaraldehyde treatment; IgE antibody production was reduced to a similar extent by all three modifications; there was no increase in IgM production; delayed reactions were reduced. New antigenic determinants were introduced by all the modifications, but the effect was minimal following glutaraldehyde treatment. The significance of these results and the potential application of modified allergen in hyposen-sitisation therapy are discussed.

Conjugates of poly-N-methylglycine (polysarcosine) and grass pollen extracts, previously found to be capable of suppressing immature IgE antibody responses in mice, were shown to be highly effective at inhibiting the capacity of immune splenocytes to produce a secondary response in sub-lethally irradiated recipient animals. Anamnestic IgE responses in mice primed without adjuvant were also suppressed, but the effects were modest and of short duration. The predictive value of murine models for selecting clinically appropriate specific IgE suppressive agents and treatment schedules that might be successfully employed for clinical use are discussed.

Serum IgE antibody responses were generated in mice by intranasal exposure to grass pollen extract. Primary IgE responses were suppressed by the concomitant intranasal administration of a conjugate of polysarcosine and pollen extract which has been shown to be a potent tolerogen when given parenterally. Partial suppression of boosted IgE responses was observed when the conjugate was applied intranasally with a secondary challenge of unmodified extract. The data suggest that clinical schedules of intranasal application of tolerogenic conjugates can be devised to bring about specific IgE suppression.

Timothy pollen extracts have been reacted with glutaraldehyde under conditions leading to different degrees of aggregation of the product. Aggregation tends to enhance the previously demonstrated effects of glutaraldehyde in that reactivity with human IgE antibody, and ability to induce IgE antibody in the Bordetella pertussis-treated rat, are further reduced. Ability to induce IgG antibody with specificity for unmodified extract is substantially retained in all aggregated products.