In Vitro Safety Profile of a Depigmented-Polymerized Peanut Allergenic Extract

Several alternatives have been developed for the treatment of peanut allergy. Safety is the most challenging issue and the main reason why subcutaneous immunotherapy has not been more extensively studied. This study aims to develop and characterize a depigmented-polymerized peanut extract designed according to their safety profile. Peanut native extract (NE) was manufactured after the extraction of the protein fraction from roasted peanuts. This fraction was dialyzed and freeze-dried. Afterwards, the NE was purified (mild acid treatment) to remove low MW substances (depigmentation) and finally polymerized with glutaraldehyde (PE). Both extracts were characterized by: Size exclusion chromatography to determine their protein profile. Allergenic activity was compared by ELISA inhibition. IgE-binding stability was measured by surface plasmon resonance (Biacore T100) using sera from allergic patients. The chromatogram of the NE showed the presence of several peaks in a distribution between 9 to 100 kDa while the PE showed a clear modification. ELISA inhibition confirmed the reduction of the IgE binding capacity of PE (10 times). The stability of the IgE in complex with Ara h 1 (Kd=0.00183 s-1 and t½=377.8 s), NE (Kd=0.00203 s-1 and t½=341.8 s) and PE (Kd=0.0042 s-1 and t ½=156.8 s) was significantly lower in PE, confirming the safety profile. A depigmented-polymerized peanut extract with an excellent profile of safety has been developed. The in vitro results demonstrated a reduction of the allergenicity while maintaining the allergen composition. Further studies are under development to confirm the safety profile in animal models.