Desensitizing mice to ovalbumin through subcutaneous microsphere immunotherapy (SMITH)

Background: We investigated whether subcutaneously-injected, biodegradable, poly (D,L-lactic-co-glycolic) acid (PLGA) microspheres loaded with ovalbumin (OVA) were able to down-regulate the T helper 2 (TH2) response in mice that were sensitized to this protein, and whether this response was dose-dependent. Methods: PLGA microspheres were created using a double emulsion technique. Female BALB/c mice were sensitized to OVA and then assigned to receive subcutaneous microsphere immunotherapy (SMITH) using either blank microspheres (n = 4), low-dose OVA-loaded microspheres (n = 5), or high-dose OVA-loaded microspheres (n = 5). Antigen-specific immunoglobulin E (IgE) in serum was measured at day 0 (prior to sensitization), day 14 (prior to immunization), and days 28 and 42 (after immunization). Results: All mice were successfully sensitized to OVA. In the group receiving blank microspheres, there was a continual rise in antigen-specific IgE from Day 14 to Day 42, which was statistically significant. In the group receiving low-dose OVA-loaded microspheres, there was a statistically significant drop in the antigen-specific IgE levels from Day 14 to Day 28, but overall no significant change in IgE level when looking at the Day 14 to Day 42 interval. A similar pattern of antibody level changes was seen in the group receiving high-dose OVA-loaded microspheres, but the decrease from Day 14 to Day 28 was not statistically significant. Conclusion: Our data suggest that SMITH has the ability to downregulate the production of antigen-specific IgE in a food allergy model, and this observation in our study was not dose-dependent. Its potential use in the treatment of IgE-mediated allergic disease warrants further investigation. © 2011 ARS-AAOA, LLC.