Why might an adjuvant combine aluminum salts with MPL?

• A. To enhance immunogenicity by stimulating innate sensing and driving a robust adaptive response
• B. To suppress innate immune activation
• C. To reduce vaccine stability
• D. To avoid B cell activation

Answer: (A)

Combining aluminum salts with MPL aims to boost a vaccine’s immunogenicity by engaging both innate sensing and the adaptive response. Aluminum salts help recruit and activate antigen-presenting cells and can help keep antigen at the injection site for better uptake. MPL, a detoxified derivative of LPS, activates TLR4 on innate immune cells, triggering signaling that matures dendritic cells and shapes the cytokine environment to promote a stronger T helper response. When used together, they act synergistically: alum supports efficient antigen presentation while MPL provides a robust innate activation signal that leads to stronger, more durable antibody production and better T cell help. This approach is about enhancing innate cues to drive a robust adaptive immune response, not about suppressing signaling, compromising stability, or avoiding B cell activation.