Preservation of mucosal and systemic adjuvant properties of ISCOMS in the absence of functional interleukin‐4 or interferon‐γ

Adjuvants are a critical component of non‐viable vaccine vectors, particularly for those to be used via mucosal routes. Although most adjuvants act by inducing local inflammatory responses, the molecular basis of many of these effects is unclear. Here we have investigated whether interleukin‐4 (IL‐4) and interferon‐γ (IFN‐γ) are required for the induction of local and systemic immune responses by oral and parenteral administration of ovalbumin (OVA) in immune stimulating complexes (ISCOMS), a potent mucosal adjuvant vector. Our results show that after oral or systemic immunization with OVA ISCOMS, IL‐4 knockout (IL4KO) and IFN‐γ receptor knockout (IFN‐γRKO) mice develop an entirely normal range of immune responses including delayed‐type hypersensitivity (DTH), serum immunoglobulin G (IgG) antibodies, T‐cell proliferation and cytokine production, class I major histocompatibility complex (MHC)‐restricted cytotoxic T lymphocyte (CTL) activity and intestinal IgA antibodies. These responses were of a similar magnitude to those found in the wild‐type mice, indicating that the immunogenicity of ISCOMS is not influenced by the presence of IL‐4 or IFN‐γ and emphasizing the potential of ISCOMS as widely applicable mucosal adjuvants.