Monoclonal antibodies to human interleukin-1 beta and their use in a sensitive two-site enzyme linked immunosorbent assay.

Five Monoclonal Antibodies (MAbs) coded respectively #111, 122, 206, 209 and 609 were produced against human recombinant Interleukin-1 beta (rIL-1 beta, amino acids 117-269). Four of these MAbs (#111, 122, 206 and 609) have been identified able to inhibit the biological activity of recombinant and natural Interleukin-1 beta. Competition studies suggested that three non-overlapping epitopes of the molecule were recognized by the MAbs. MAbs #609 and 206 have been selected on the basis of high affinity and used together in a two-site ELISA to detect IL-1 beta. The sensitivity of this ELISA was 1 pg/well (10-20 pg/ml). The assay did not detect rHuIL-1 alpha, rHuIL-2, rHuTNF-alpha, rHuIFN-gamma, rHuIL-6, and natural a- and b-FGF. The immunoassay was then compared to current assay such as co-mitogenic effect on murine thymocytes for detection of IL-1 beta in the intra- and extracellular compartments of IFN-gamma and/or LPS-stimulated human blood monocytes. We confirm that IFN-gamma potentiates IL-1 beta secretion in response to LPS (even with high dose 1 microgram/ml) but not the intracellular precursor of IL-1 beta. This immunoassay could be used also to detect IL-1 beta in plasma, sera and synovial fluids.