Expression of rat interleukin-5 and generation of neutralizing antiserum: a comparative study of rat IL-5 produced in Escherichia coli and insect cells

A cDNA coding for rat IL-5 was obtained by RT-PCR from total spleen RNA. Wi th the exception of a single a.a. replacement at position 85 (L-P), it is i dentical to the published sequence obtained by retroviral gene transfer. Th is cDNA was used to express biologically active recombinant IL-5 in E. coli and in insect cells using a baculovirus system. Rat IL-5 is more active on B13, an IL-5 dependent cell line, when produced in insect cells (specific activity 1.47 x 10(11) UI/mg compared to 4.28 x 10(6)UI/mg). This increased activity seems to be associated with the presence of IL-5 homodimers in re combinant protein preparations. A rabbit antiserum raised against recombina nt bacterial IL-5 specifically inhibited B13 proliferation induced by bacte rial and baculoviral IL-5. The availability of such reagents should facilit ate studying the role of IL-5 in different infectious diseases, experimenta l allergic encephalomyelitis and in transplantation biology where the rat r epresents a more suitable model than mice. (C) 1998 Academic Press.