Interleukin-17A (IL-17A) is involved in antibody specificity to conformational epitopes

The specificity of antibodies (Ab) is essential for the precise recognition of foreign or dangerous molecules. We have shown that mice infected with non-pathogenic Lactate Dehydrogenase Elevating Virus (LDV) inoculated with human growth hormone (hGH) or Ovalbumin (OVA), exhibit modified specificity of anti-hGH or anti-OVA Ab associated with the secretion of IFN-γ, IL-13, and IL-17. Cytokines are directly or indirectly involved in the isotypes, specificity, and affinity of Ab. Accordingly, here we investigated the effect of IL-17 neutralization on Ab specificities to OVA and Diphtheria Toxoid (DTx) in a mouse model of viral infection. Thereby, we employed an anti-cytokine "auto-vaccination" with an OVA/IL-17A complex or a Monoclonal Ab (MAb) anti-IL-17A (MM17/F3). Competitive ELISA assays were used to estimate the quality of the humoral immune response and the amount of Abs to conformational versus linear antigenic determinants. Results indicated that the OVA/IL-17A complex increased Abs levels to conformational epitopes of OVA, while LDV prolonged antibodies for a longer period. Mice treated with MM17F3 MAb showed an increase in Abs to conformational epitopes of OVA. A similar effect, confirmed by a competitive Western-blot assay, was produced by LDV. Moreover, an increased level of IgM, IgG1, and IgG2a was found in infected animals. Similarly, MAb anti-IL-17A treatment increased the proportion of Ab to conformational epitopes of DTx in uninfected mice, while LDV decreased this parameter. In conclusion, our findings demonstrate a correlation between IL-17A neutralization and a change in Ab specificity to OVA or DTx, presenting a novel strategy for obtaining Abs with higher specificity.