Purpose. Spray-dried lipid-based microparticles (SDLM) serve as a platform
for delivery of a wide variety of compounds including peptides, proteins, a
nd vaccines to the respiratory mucosa. In the present study, we assessed th
e impact of IgC-mediated targeting to phagocytic cells of inactivated influ
enza virus formulated in SDLM, on subsequent immune responses.
Methods. SDLM were produced containing inactivated influenza virus strain A
/WSN/32/H1N1 (WSN), with or without IgG. Using phagocytic antigen presentin
g cells (APC) and a T cell hybridoma (TcH) line specific for a dominant inf
luenza virus epitope, we compared the in vitro responses elicited by ligand
-formulated (SDLM-IgG-WSN) and non-ligand particles (SDLM-WSN). The effect
of including the IgG ligand in the formulation was further characterized by
measuring the immune responses of rodents vaccinated with SDLM.
Results. SDLM-IgG-WSN were internalized in an Pc receptor (FcR)-dependent m
anner by phagocytic APC that were then able to effectively present a domina
nt, class II-restricted epitope to specific T cells. While SDLM-WSN elicite
d a lower response than administration of plain inactivated virus in saline
, the level of the T cell response was restored both in vitro and in vivo b
y incorporating the APC FcR ligand, IgG, in the SDLM.
Conclusions. Incorporation of FcR ligand (IgG) in SDLM restored the limited
ability of formulated virus to elicit T-cell immunity, by receptor-mediate
d targeting to phagocytes.