Quantitation of human interleukin-1 beta with polyclonal antibodies

Polyclonal antisera to human recombinant interleukin-1 beta have been developed in rabbits and mice. When measured by indirect enzyme-linked immunoassays, the antisera bound rIL-1 beta in a dose-dependent manner but did not bind to rIL-1 alpha or murine rIL-1. Both antisera specifically neutralized thymocyte activation induced by rIL-1 beta or normal monocyte IL-1 and growth inhibition induced by rIL-1 beta. The antiserum specificities led us to examine a double antibody ELISA for quantitating IL-1 beta. The linear portion of the standard curve from an ELISA against rIL-1 beta ranged from 0.5 to 10.0 half-maximal units of [3H]thymidine incorporation in mouse thymocyte cultures. A similar correlation was observed using monocyte derived IL-1 from two sources. The major result of this work was the observation that polyclonal antibodies made against a recombinant molecule also recognized natural IL-1. We suggest that these antisera recognize epitopes unique to IL-1 beta which reside at or near regions of the molecule responsible for biological activity.