Production and in vitro characterization of recombinant chicken interleukin-2

Mammalian interleukin-2 (IL-2) is a well-characterized cytokine that plays key roles in T cell differentiation and activation, B cell development, and natural killer (NK) cell stimulation. Chicken IL-2, which is the first non mammalian IL-2 cloned, differs substantially from mammalian IL-2 molecules. We undertook to study the functions of chicken IL-2 by producing recombina nt molecules in prokaryotic and eukaryotic expression systems, determining the in vitro properties of these molecules, and examining the kinetics of e ndogenous IL-2 production in vitro, Recombinant chicken IL-2 (rChIL-2) prod uced in prokaryotic and eukaryotic expression systems induced proliferation of chicken splenocytes in vitro, demonstrating that glycosylation is not r equired for this activity, Polyclonal antibodies generated against prokaryo tically produced rChIL-2 inhibited proliferation of splenocytes induced by eukaryotically and prokaryotically produced rChIL-2, as well as endogenousl y produced cIL-2 obtained from ConA-stimulated splenocytes, Human IL-2 or I L-15-induced CTLL proliferation was not blocked by rChIL-2 or polyclonal an ti-rChIL-2 antibodies, indicating that chicken IL-2 cannot act as an antago nist of the mammalian IL-2 response. Endogenous chicken IL-2 appears to occ ur in vitro as a monomer of about 14.2 kDa and is secreted within 4 h after ConA stimulation, The production of rChIL-2 provides us with a useful tool for studying avian immunology as well as a potential vaccine-enhancing age nt.