Elucidating the systemic humoral response and immune microenvironment at the implant interface of the Vaccine Platform for Extended Antigen Release (VPEAR) 9238

Abstract Description The Vaccine Platform for Extended Antigen Release (VPEAR) is an implantable device with a polyanhydride depot that sustains the release of the model antigen ovalbumin (OVA) and the adjuvant CpG ODN 1826 for over 24 weeks. A PVDF membrane cap serves as an immune interface, which also prevents cellular infiltration into the depot. Compared to bolus vaccinated mice, VPEAR-implanted animals exhibit consistently higher serum levels of OVA-specific IgG. VPEAR implanted animals also show increased OVA-specific IgG-secreting cells (ISCs) in lymph nodes by week 12 post-vaccination. Histological analysis of the immune interface reveals a highly vascularized tissue layer, while ELISpot assays confirm enrichment of OVA-specific ISCs on the cap. B220+ GL7+ cells also persist on the cap for over 24 weeks, suggesting germinal center activity. Preliminary qPCR data show elevated CXCL13 expression, critical for B-cell zone formation, and CCL5, a recruiter of T cells and monocytes, but no upregulation of CCL21, which is associated with T-cell zones. These findings suggest VPEAR elicits a robust humoral response with sustained B-cell activity at the cap, which may be consistent with a B-cell-dominated tertiary lymphoid structure. Topic Categories Vaccines and Immunotherapy (VAC)