Characterization of an IL-6-like molecule from an echinoderm (Asterias forbesi)

Our previous studies have demonstrated the presence of two of the three vertebrate inflammatory cytokines in invertebrates, namely, interleukin (IL)-1 and tumour necrosis factor (TNF), We studied the coelomic fluid of the echinoderm, Asterias forbesi, to determine whether it contained the third inflammatory cytokine, IL-6, Coelomic fluids were concentrated and then fractionated by a combination of gel sieve chromatography and preparative isoelectric focusing, The M(r) observed for the invertebrate IL-6-like molecule was approximate to 30 000 and the pI was 5.5, Western blot analysis using a polyclonal rabbit antiserum to human IL-6 detected a band at approximate to 30 000 Da, The invertebrate IL-6 was inhibited by an antiserum to human IL-6 when used in the B9 assay Finally, the coelomocytes were found to be capable of releasing the IL-6-like molecule as early as 12 h following stimulation by LPS, These results, together with our other data, show that echinoderms possess correlates of all three vertebrate inflammatory cytokines. (C) 1996 Academic Press Limited