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 nonmammalian IL-2 cloned, differs substantially from mammalian IL-2 molecules. We undertook to study the functions of chicken IL-2 by producing recombinant molecules in prokaryotic and eukaryotic expression systems, determining the in vitro properties of these molecules, and examining the kinetics of endogenous IL-2 production in vitro. Recombinant chicken IL-2 (rChIL-2) produced in prokaryotic and eukaryotic expression systems induced proliferation of chicken splenocytes in vitro, demonstrating that glycosylation is not required for this activity. Polyclonal antibodies generated against prokaryotically produced rChIL-2 inhibited proliferation of splenocytes induced by eukaryotically and prokaryotically produced rChIL-2, as well as endogenously produced cIL-2 obtained from ConA-stimulated splenocytes. Human IL-2 or IL-15-induced CTLL proliferation was not blocked by rChIL-2 or polyclonal anti-rChIL-2 antibodies, indicating that chicken IL-2 cannot act as an antagonist of the mammalian IL-2 response. Endogenous chicken IL-2 appears to occur 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 agent.

Determination of a process intermediate of celiprolol and its potential impurities by gradient high-performance liquid chromatography--application of high-low chromatography.

3-(3-acetyl-4-hydroxyphenyl)-1,1-diethylurea (A-1354), is a synthetic intermediate of the beta-adrenergic blocker, celiprolol hydrochloride. A liquid chromatographic method has been developed and validated for the determination of bulk A-1354 and its potential impurities. High-low chromatography was used to improve the detectability of trace impurities. Enhanced chemical detectability was achieved by comparing the detector response of trace-impurity peaks from a stock sample solution (high-concentration) with the detector response for the A-1354 peak in a quantitatively diluted working sample solution (low-concentration). Chromatographic separation was achieved by gradient elution of A-1354 and its known impurities using an Ultrasphere C18 analytical column (5 microns, 250 x 4.6 mm i.d.). The gradient mobile phase components were methanol and 0.1% triethylammonium phosphate, pH = 4.0. The flow rate was 0.9 ml min-1 with UV absorbance detection at 236 nm. The method was determined to be specific, linear, precise and accurate for A-1354 and its known impurities. Known impurities of A-1354 are quantitated to 0.05% (w/w).