Aggregated Recombinant Human Interferon Beta Induces Antibodies but No Memory in Immune-Tolerant Transgenic Mice

PURPOSE: To study the influence of protein aggregation on the immunogenicity of recombinant human interferon beta (rhIFNbeta) in wild-type mice and transgenic, immune-tolerant mice, and to evaluate the induction of immunological memory. METHODS: RhIFNbeta-1b and three rhIFNbeta-1a preparations with different aggregate levels were injected intraperitoneally in mice 15x during 3 weeks, and the mice were rechallenged with rhIFNbeta-1a. The formation of binding (BABs) and neutralizing antibodies (NABs) was monitored. RESULTS: Bulk rhIFNbeta-1a contained large, mainly non-covalent aggregates and stressed rhIFNbeta-1a mainly covalent, homogeneous (ca. 100 nm) aggregates. Reformulated rhIFNbeta-1a was essentially aggregate-free. All products induced BABs and NABs in wild-type mice. Immunogenicity in the transgenic mice was product dependent. RhIFNbeta-1b showed the highest and reformulated rhIFNbeta-1a the lowest immunogenicity. In contrast with wild-type mice, transgenic mice did not show NABs, nor did they respond to the rechallenge. CONCLUSIONS: The immunogenicity of the products in transgenic mice, unlike in wild-type mice, varied. In the transgenic mice, neither NABs nor immunological memory developed. The immunogenicity of rhIFNbeta in a model reflecting the human immune system depends on the presence and the characteristics of aggregates.