Adjuvantation of epidermal powder immunization.

Area of Science:

• Immunology
• Vaccinology

Background:

• The skin is a highly immune-active organ, making it a promising vaccination route.
• Current vaccine administration methods include oral, intramuscular, and subcutaneous injections.
• Previous research demonstrated that epidermal powder immunization (EPI) with a minimal dose of influenza vaccine powder can elicit protective immunity in mice.

Purpose of the Study:

• To investigate the efficacy of commonly used adjuvants in enhancing immune responses via EPI.
• To assess the impact of adjuvants on antibody production, toxin-neutralization activity, and T helper cell subset activation during EPI.

Main Methods:

• Epidermal powder immunization (EPI) was employed using diphtheria toxoid (DT) co-delivered with adjuvants: aluminum phosphate (alum) and CpG DNA motifs.
• Immune responses were evaluated by measuring IgG antibody levels, toxin-neutralization activity, and the activation of T helper cell subsets (Th1/Th2).
• Specific immune markers such as IgG1, IgG2a, IL-4, and IFN-gamma were quantified.

Main Results:

• Co-administration of DT with alum or CpG DNA via EPI significantly augmented IgG antibody responses (25- and 250-fold, respectively).
• The induced antibodies exhibited long-lasting toxin-neutralization activity.
• EPI with adjuvants selectively modulated T helper cell responses, with alum promoting Th2-type immunity (IgG1, IL-4) and CpG DNA promoting Th1-type immunity (IgG2a, IFN-gamma).

Conclusions:

• Epidermal powder immunization (EPI) combined with appropriate adjuvants can significantly enhance both antibody and cellular immune responses.
• EPI is a versatile and promising immunization strategy capable of delivering various vaccines, including those formulated with adjuvants.
• This approach offers potential for developing more effective and potentially less invasive vaccination methods.