Antigenic differences between natural and recombinant murine IL-1.

Natural (n) interleukin 1 (IL-1) and recombinant (r) IL-1 alpha of murine P388D1 cell line origin were investigated for their antigenicity in rabbits. Both nIL-1 and rIL-1 alpha evoked an antibody response. By solid-phase radioimmunoassay, anti-nIL-1 antibodies bound nIL-1 and rIL-1 alpha equally well; in contrast, the anti-rIL-1 alpha antibodies bound homologous rIL-1 alpha significantly more than nIL-1 suggesting either a lack of antibodies directed against certain epitope(s) on nIL-1 or presence of low affinity antibodies. Moreover, unlike anti-nIL-1 antibodies, anti-rIL-1 antibodies failed to inhibit augmentation of thymocyte proliferation by either IL-1. Thus, antigenic differences between nIL-1 and rIL-1 alpha appear to elicit an overlapping but different antibody response in rabbits.