Molecular cloning and physiological effects of brushtail possum interleukin-1 beta

Interleuhin-1 beta (IL-1 beta) was isolated from LPS-stimulated brushtail p ossum alveolar macrophages using PCR primers based on conserved regions of mammalian IL-1 beta. The complete cDNA was cloned by 5' and 3' rapid amplif ication of cDNA ends (RACE). The predicted protein of 269 amino acids share d 43-46% identity with several mammalian IL-1 beta proteins. Constructs wer e made to express the mature IL-1 beta in Escherichia coli and two recombin ant IL-1 beta proteins, rpIL-1 beta 1 and rpIL-1 beta 2, which differed in length by four amino acids at the N-terminus, were produced. Both proteins induced a weak proliferative response in a possum thymocyte assay. Possums injected intravenously with 100 mu g of rpIL-1 beta 1 or rpIL-1 beta 2 show ed profound changes in body temperature and numbers of circulating leukocyt es. A sharp decrease in temperature occurred within 2 h of administration f ollowed by an elevation of temperature peaking at 24 h. The smaller rpIL-1 beta 1 protein had a greater effect on temperature than rpIL-1 beta 2. Both rpIL-1 beta proteins caused a marked decrease in number of neutrophils and lymphocytes at 2-6 h after injection. At 24 h after injection, neutrophil and lymphocyte numbers were elevated 6.0-fold and 2.6-fold, respectively in the possums injected with rpIL-1 beta 1 and 3.9-fold and 1.5-fold, respect ively in the possums injected with rpIL-1 beta 2. Fibrinogen levels were el evated at 24 and 72 h after injection with both proteins. In comparison, ne ither recombinant bovine IL-1 beta (rbIL-1 beta) nor PBS had significant ef fects on body temperature or blood haematology. The studies have shown that the two recombinant forms of IL-1 beta were biologically active in possums and that the IL-1 beta with four fewer amino acids at the N-terminus was t he more active. (C) 1999 Elsevier Science B.V. All rights reserved.