Immunological characterization of antigenic domains on XXXX @entity3647 subunit: epitope-function relationships.

@entity1199 @entity1 @entity3647
Five mAb directed at the @entity3647 chain were analyzed for their binding and functional properties. They define three epitopes on a recombinant soluble beta chain or on the beta chain expressed at the surface of YT-2C2 cells. Epitope 1 (A41 and 6E8 mAb) is part of the @entity1199 binding domain, whereas epitope 2 (CF1 and 6E10 mAb) is not involved in @entity1199 binding. Epitope 3 (6B5 mAb) also partly overlaps the @entity1199 binding domain but does not overlap epitopes 1 and 2. None of the mAb can by themselves inhibit @entity1199 induced proliferation of a @entity1 activated T cell clone. Only epitope 1 mAb can synergize with an anti-alpha chain mAb to inhibit this proliferation. Using epitope 1 and 2 mAb as well as a purified, recombinant form of the @entity3647 chain extracellular domain, an ELISA-based immunoassay was set up which allows the quantitative determination of soluble and detergent solubilized @entity3647 chains. Epitopes 1 and 2 are in non-competitive interaction: the binding of a mAb to one epitope decreases the affinity of a mAb for the second epitope. Epitope 2 mAb have binding stoichiometries (approximately 16,000 sites/cell) which are approximately 80% higher than that of epitope 1 mAb and @entity1199 itself (approximately 9000 sites/cell). Upon binding of epitope 2 mAb, the stoichiometries of epitope 1 mAb and @entity1199 are increased to reach the stoichiometry of epitope 2 mAb.(ABSTRACT TRUNCATED AT 250 WORDS)
