COMPARISON OF ANTIBODY-PRODUCTION TO HUMAN INTERLEUKIN-6 (IL-6) BY SHEEP AND CHICKENS

Chicken antibodies have been reported to provide an excellent alternat ive to their mammalian counterparts for immunodiagnostics, but detaile d studies, particularly regarding their avidity, are limited. Prior to the development of an immunoassay for measuring human interleukin-6 ( hIL-6) we compared the serum antibody responses of sheep and chickens to immunization with recombinant human IL-6 (rhIL-6) and studied the t ransfer of chicken serum antibodies to the egg yolk. Both chickens and sheep produced high avidity antisera (average avidity constants being 1.3 x 10(10) l/mol and 3.1 x 10(10) l/mol respectively after four imm unizations) with chickens producing an unusually high avidity response after a single immunization. Although both antisera showed extremely high specificity for their ligand, both demonstrated a high degree of recognition for Chinese hamster ovary cell-derived IL-6 (CHO-IL-6), a glycosylated form of recombinant human interleukin-6 (rhIL-6) more aki n to natural hIL-6. A delay of 3-4 days was found between the appearan ce of serum anti-IL-6 antibodies and their detection in the egg yolk; specific antibody in the latter was concentrated by a factor of 1.23 /- 0.07 relative to serum. The binding characteristics of paired serum and yolk antibodies with respect to both rhIL-6 and CHO-IL-6 were ide ntical. These studies demonstrate the suitability of both chickens and sheep as hosts for the production of large quantities of high quality antiserum to human IL-6.