Methods: BALB/cJ mice received intravenous injections of either PBS (n=6), 100 uM antigenic liposome displaying Ah2 only (n=8), 20 uM Ah2 STALs (n=6), or 100 uM Ah2 STALs (n=7). After two weeks, mice were sensitized by gavage with crude peanut extract and cholera toxin once weekly for 4 weeks. Mice were bled and challenged with intraperitoneal Ah2. Serology and challenge results were compared between groups.
Results: Compared to PBS controls, injection with 100 uM STALs led to lower Ah2-specific IgG1 (p=0.002) and IgE (p=0.008). Ah1-specific IgE (p=0.008) and IgG2a (p=0.006) were also lower in mice treated with 100 uM STALs compared to placebo. Treatment with 20 uM Ah2 STALs had no significant effect on Ah2- or Ah1-specific IgG1, IgG2a, or IgE, suggesting a dose effect. Upon challenge, the group pre-treated with 100 uM Ah2 STALs maintained a stable body temperature (slope parameter [±SD] -0.040±0.025; p=0.122 for a non-zero slope) unlike mice treated with PBS, that displayed the expected anaphylactic response (-0.099±0.031; p=0.006).
Conclusions: Pre-treatment with 100 uM tolerogenic Ara h 2-loaded STALs leads to lower Ah2- and Ah1-specific IgE and protects from experimental peanut anaphylaxis.