Novos adjuvantes: determinação do perfil imunomodulador do polissacarídeo xantana produzido por Xanthomonas arboricola pv. pruni 106

Abstract

The successful production of new, safe and effective vaccines that generate immunological memory is directly related to adjuvant feature, which is responsible for increasing and/or modulating the immune response. Several compounds display adjuvant activity, including carbohydrates. One such carbohydrate is xanthan gum, a polysaccharide that is produced by the plant pathogenic bacterium Xanthomonas spp. This polysaccharide has been explored for having adjuvant properties. However, aspects related to its immunomodulatory mechanism remain unexplored. This study evaluated the immune response induced by xanthan gum associated with ovalbumin (OVA) in BALB/c mice, that were subcutaneously immunized. Seven animals were divided into: OVA-xanthan (0.5% v/v), OVA-Alhydrogel (15% v/v), OVA-saline and saline. After the immunization regimen, the antibody production (IgG1, IgG2a, IgG2b, and IgG3) and assessed the levels of INF-γ in the splenocyte culture using ELISA indirect. Furthermore, we investigated in vitro cytotoxicity of xanthan (0.1-1% v/v) in the embryo fibroblasts cell line of the NIH/3T3 mouse by MTT assay and propidium iodide uptake assay. The mice immunized with ovalbumin plus xanthan gum exhibited higher antibody IgG1 responses than those immunized with the ovalbumin without adjuvant. Furthermore, the xanthan polysaccharide was capable of increasing the immunogenicity of antigens by producing INF-γ and did not exhibit cytotoxicity effects in NIH/3T3 mouse fibroblast cells, demonstrating the potential of using xanthan as a vaccine adjuvant combined with protein antigens.