Conjugates of poly-N-methylglycine (polysarcosine) and grass pollen allergen extracts, which have been previously shown to suppress murine IgE responses, were examined for their ability to modify lymphocyte activity in vitro. Allergen-specific T lymphocytes obtained from Balb/c mice gave a reduced response to syngeneic accessory cells pulsed with conjugates of polysarcosine-allergen compared with the response found using equivalent concentrations of native extract. Pretreatment of accessory cells with either polysarcosine or polysarcosine-allergen conjugates did not impair their subsequent ability to present grass pollen extract to immune T cells. Incubation of allergen-specific spleen cells with polysarcosine-allergen conjugates, but not with polysarcosine or allergen alone, resulted in specific cell-mediated suppression which significantly reduced proliferation in vitro. This activity was sensitive to treatment of cells with anti-T-lymphocyte antisera plus complement. Spleen cells obtained from animals immunised with allergen and taken 21 days after intravenous treatment with polysarcosine-allergen conjugates, a regimen that suppressed IgE antibody production, did not proliferate in the presence of grass pollen extract and failed to suppress a secondary lymphoproliferative response in vitro. Spleen cells obtained from similarly treated animals 3 days after the final polysarcosine-allergen injection responded to pollen extract in culture and, additionally, impaired a secondary response. The results suggest that the reduced IgE response found in animals treated with polysarcosine-allergen conjugates may be due, in part, to the generation of a short-lived antigen-specific T cell suppression.
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