ARNAX, but not conventional adjuvants, alum and squalene, induces antigen-specific CD8+ T cell proliferation in vaccination with influenza split vaccine

The influenza split vaccine (ISV) is generally administered without adjuvant via intra-muscular (i.m.) or intranasal route. Research has demonstrated that SV alone exhibits no capacity to elicit a Th1 (T helper-1) response and cellular immunity represented by cytotoxic T lymphocytes (CTL) induction. This finding is consistent with the observation that SV merely up-regulates antibody (Ab) production in the pre-disposed population. This tendency is reproduced in the SV model in conjunction with conventional adjuvants, including alum or squalene. These adjuvants amplify the Th2 shift, consequently stimulating Th2-dependent Ab production in mice. Conventional adjuvants, when employed with SV in animal studies, demonstrate a limited capacity to stimulate cellular immune activation. The present study aims to demonstrate the efficacy of a Th1-inducing adjuvant, ARNAX, in promoting antigen-presenting DC and subsequent Ag-specific CTL proliferation, culminating in Th1 polarization. Consequently, the synthesis of the two effectors, CTL and Ab, is augmented by the incorporation of ARNAX in SV. The enhanced SV-mediated protective immunity may be further augmented by the induction of antigen-specific CTL and the unique profile of Th1-mediated Ab production.