Infectious disease vaccine potency is affected by
antigen adjuvant adsorption. WHO and EMA guidelines recommend limits and experimental monitoring of adsorption in
vaccines and
allergy immunotherapies. Adsorbed
allergoids and MPL® in MATA-MPL
allergy immunotherapy formulations effectively treat
IgE mitigated
allergy. Understanding
vaccine antigen adjuvant adsorption allows optimisation of potency and should be seen as good practice; however current understanding is seldom applied to
allergy immunotherapies. The
allergoid and MPL® adsorption to MCT in MATA-MPL
allergy immunotherapy formulations was experimental determination using specific
allergen IgE allerginicity and MPL® content methods. Binding forces between MPL® and MCT were investigated by competition binding experiments. MATA-MPL samples with different
allergoids gave results within 100-104% of the theoretical 50μg/mL MPL® content. Unmodified
drug substance samples showed significant desirable
IgE antigenicity, 1040-170 QAU/mL. MATA-MPL supernatant samples with different
allergoids gave results of ≤2 μg/mL MPL® and ≤0.1-1.4 QAU/mL
IgE antigenicity, demonstrating approximately ≥96 & 99% adsorption respectively.
Allergoid and MPL® adsorption in different MATA-MPL
allergy immunotherapy formulations is consistent and meets guideline recommendations. MCT formulations treated to disrupt electrostatic, hydrophobic and
ligand exchange interactions, gave an MPL® content of ≤2 μg/mL in supernatant samples. MCT formulations treated to disrupt aromatic interactions, gave an MPL® content of 73-92 μg/mL in supernatant samples. MPL® adsorption to
l-tyrosine in MCT formulations is based on interactions between the 2-deoxy-2-aminoglucose backbone on MPL® and aromatic ring of
l-tyrosine in MCT, such as C-H⋯π interaction. MCT could be an alternative adjuvant depot for some
infectious disease antigens.