Vaccination
IBH is a Th2 type, IgE mediated allergy with an imbalance between Th1, Th2 and Treg (Hamza et al., 2007; Hamza et al., 2010; Hamza et al., 2008; Heimann et al., 2011). Allergen immunotherapy (AIT) based on the disease-causing allergens is the only curative treatment for type I allergies (Dorofeeva et al., 2020, López et al., 2022).
For prophylactic immunotherapy to prevent allergic sensitization it is therefore important to use Th1/Treg focusing adjuvants or agents to induce and/or rebalance the Th1:Th2:Treg responses and restraint the inflammatory mechanisms. The route of injection has also to be considered and we have shown that injecting directly into the lymph nodes with the appropriate adjuvant is a promising option (Jonsdottir et al., 2015; Jonsdottir et al., 2016).
Vaccination with purified allergens in Alum/monophosphoryl lipid A (MPL), but not in Alum alone, resulted in a Th1/Treg focused immune response. The IgG antibodies induced, efficiently blocked the binding of IgE from IBH horses to the allergens (Jonsdottir et al., 2016). It has been demonstrated that allergen-specific IgG antibodies that compete with IgE for binding to the allergens are one of the major mechanisms in successful AIT (Durham and Shamji., 2022). The intralymphatic vaccination with purified allergens in Alum/MPL has now been reinforced in more horses and compared to subcutaneous vaccination a more practical injection route (Stefánsdóttir et al., 2022).