SPECIES-SPECIFIC ACTIVITY OF RAT RECOMBINANT INTERLEUKIN-1-BETA

We have constructed expression clones for mature rat interleukin-1 bet a (IL-1 beta). Using these clones, rat recombinant IL-1 beta (rrIL-1 b eta) was prepared and purified by a single-step cation-exchange chroma tography method, In addition, synthetic rrIL-1 beta mRNA was transcrib ed and used to synthesize radiolabeled S-35-rrIL-1 beta for binding st udies, The rrIL-1 beta produced was demonstrated to have IL-l bioactiv ity in a mouse thymocyte proliferation assay, in which it could be blo cked by inclusion of human recombinant IL-I receptor antagonist (hrIL- 1Ra), Similarly, rrIL-1 beta induced LIF mRNA expression in cultured r at sympathetic ganglia, In each case, the maximal dose of rrIL-1 beta was similar to that of human IL-1 beta, However, the peak response in rat tissue was twofold higher with rat IL-1 beta than with human IL-1 beta, The expression of rrIL-1 beta provides a useful tool for studyin g IL-1 receptors in rat, in which human and mouse IL-1 beta have been found to bind poorly, Species-specific activity of rat IL-1 beta may c orrelate with compensatory ionic properties of rat IL-1 receptor.