Analysis of ovine IL-1β production in vivo and in vitro by enzyme immunoassay and immunohistochemistry

A monoclonal antibody (mAb) specific for ovine IL-1β was produced and, in conjunction with a polyclonal rabbit antiserum, used to develop a sensitive enzyme immunoassay (EIA) for ovine interleukin 1β (IL-1β). The mAb neutralised the activity of recombinant ovine IL-1β (rOvIL-1β) and native OvIL-1 in an ovine thymocyte proliferation assay. However, it did not neutralise the biological activity of rOvIL-1β in the murine NOB1CTLL assay. The mAb did not react with rOvIL-1α, IL-2, IL-4, IL-8, tumor necrosis factor-α, gamma-interferon or recombinant human IL-1β in indirect EIA. Immunohistological staining of activated alveolar macrophages and frozen lymph node sections demonstrated that the mAb detected IL-1β secreted by ovine macrophages (CD11c-positive). The EIA was highly sensitive, detecting less than 50 pg ml−1 of rOvIL-1β and low levels of native IL-1β in supernatants from lipopolysaccharide-stimulated macrophages. The EIA did not detect heat-inactivated IL-1β.