FUNCTIONAL EPITOPE MAPPING OF HUMAN INTERLEUKIN-1-BETA BY SURFACE-PLASMON RESONANCE

A panel of monoclonal antibodies to human IL-1 beta has been used to p robe its conformational and functional characteristics. Real time anti body-protein interaction was assessed by surface plasmon resonance wit h a BIAcore(R) apparatus, in order to determine the kinetic and thermo dynamic parameters of the interaction and to map the recognition sites of the antibodies on the IL-1 beta surface, Topological analysis was thus compared to the inhibitory capacity of antibodies for IL-1 beta b ioactivity and binding to the activating receptor IL-1R(1). This funct ional mapping analysis allows the following hypothesis, At least two d iscrete areas of IL-1 beta, located within the sequences 133-147 and 1 77-186 (as defined by mAbs MhC1 and BRhD2, respectively), are apparent ly involved in IL-1R(1)-independent agonist activity, and thus possibl y take part in the interaction with the receptor accessory protein IL- 1RAcP. Another area in the 133-147 sequence (defined by mAb BRhC3) is involved in agonist binding to its receptor CDw121a (IL-1R(1)), wherea s a site recognized by mAb BRhG5 within the sequence 218-243 is select ively responsible for non-agonist binding to the activating receptor, The loop between the 4th and the 5th beta-strand, at the open end of t he IL-1 beta-barrel structure, may possibly take part in both non-agon ist binding to IL-1R(1) and in the interaction with IL-1RAcP.