Immune response elicited by graphene oxide-based nanovaccine

Abstract

Objective To study the antigen-specific immune response induced by the graphene oxide (GO) in mice. Methods OVA-loaded GO nano-immunocomplexes (GO-OVA) were prepared by co-incubation of nano GO with model antigen ovalbumin (OVA). Nano GO was characterized by atomic force microscopy and laser particle size analyzer. The cytotoxicity of GO to mouse bone marrow dendritic cells (BMDCs) was detected by cell counting kit (CCK-8). The GO-OVA uptake of BMDCs were observed by fluorescent staining. C57BL/6 mice were divided into OVA group, aluminum adjuvant OVA (Al-OVA) group and GO-OVA group (6 mice in each group) by body weight for in vivo immunization. The levels of OVA-specific antibody IgG (total IgG, IgG1, and IgG2a) in serum of mice were detected by enzyme-linked immunosorbent assay (ELISA). The T lymphocyte subsets in spleen and inguinal lymph nodes of mice were detected by flow cytometry. Results The average particle size of the prepared nano GO was (294.34±4.68) nm, and the polydispersity coefficient was 0.208. Nano GO has less toxicity to mouse BMDCs. The results of in vitro experiments indicated that GO-OVA nanovaccine can be efficiently internalized by mouse BMDCs. The antigen-specific IgG antibodies induced by the GO-OVA was similar to that of aluminum adjuvant and the difference was not statistically significant (P>0.05), and the Th1-type response was predominant. The proportions of CD4+ and CD8+ T lymphocytes in the spleen and inguinal lymph nodes in GO-OVA group were significantly higher than those in OVA and Al-OVA groups, and the differences were statistically significant (all P<0.05). Conclusions GO-OVA nano-immunocomplexes can induce both humoral and cellular immune responses in mice, which provides basis for the development of novel vaccine vectors and adjuvants. Key words: Graphene oxide; Nanovaccine; Humoral immune response; Cellular immune response