Human interleukin-1 receptor antagonist: Large-scale expression in Bacillus brevis 47-5Q

Interleukin-1 receptor antagonist (IL-1RA) has been used as a tool to study the biologic activity of IL-1 and as a possible therapeutic substance for inflammatory disease. To perform in vivo study, however, large quantities o f IL-1RA are required. Bacillus brevis strains secrete large amounts of pro tein but little protease into the medium. Using B. brevis 47-5Q, we develop ed a large-scale expression system of human IL-1RA (HuIL-1RA), The bacteria secreted HuIL-1RA into the culture medium at very high levels, approximate ly 200 mg/L. The protein was isolated in one-step purification with monoclo nal antibody (mAb) against HuIL-1RA, The IL-1RA molecule was determined to be functionally active by the inhibiting assay of HuIL-1-induced cell proli feration in a mouse T cell line, D10N(4)M.