Development of a simple IgE-independent anaphylactic model using buckwheat antigen and B-type CpG oligodeoxynucleotide from Streptococcus thermophilus.

We developed a severe anaphylactic model in mice using buckwheat antigen and B-type CpG-oligodeoxynucleotides (CpG-ODNs) from Streptococcus thermophilus genome. In typical systemic anaphylaxis models, animals are challenged with large quantity of antigens via an intravenous (i.v.) route. Here, we showed a simple anaphylactic shock after challenge via intraperitoneal (i.p.) route. The i.p. method is simpler than i.v. administration and has a lower risk for failure. To generate this anaphylactic model, 5-week-old female BALB/c mice were first i.p. sensitized with buckwheat antigen mixed with B-type CpG-ODN. After 2 weeks, mice were challenged with antigen to induce anaphylactic shock, which was evaluated by scoring the severity symptoms and measuring serum levels of various proteins and splenic cell producing cytokines. Immunoglobulin (Ig)G2a production and interferon-γ positive cells were markedly increased in mice immunized with antigen mixed with B-type CpG-ODN, whereas serum IgE levels were decreased by B-type CpG-ODN. We also examined the effects of various ODNs (A, B and C-type CpG-ODNs) and antigens (buckwheat, α-casein, β-lactoglobulin and ovalbumin) on anaphylactic severity, and found that the combination of buckwheat and B-type CpG-ODN induced the most intense anaphylactic shock. This model is expected to contribute to the study of the prevention of anaphylactic shock.