METHODS: In a phase 1 single-center study, 9 subjects between 5-12 years with peanut allergy on POIT underwent immune evaluation at 0, 6, 12, 18 and 24-week time points after initiation of therapy and were compared to 7 healthy controls. The distribution of peanut specific Treg subpopulations and peanut and Ara h2 IgE values were measured in vitro. One-way ANOVA was used for analysis.
RESULTS: Type-1 regulatory (Tr1) T-cell (CD4+CD25+FOXP3-LAG3+CD49b+) frequencies showed a significant fluctuation over the course of evaluation (p=0.012), while Treg (CD4+CD25+FOXP3+CD73+LAP+) frequencies and total Treg populations (CD4+CD25+FOXP3+) showed no significant change (p=0.709 and p=0.315, respectively). The cohort baseline median peanut IgE was 62.5 kU/L (20-329) and Ara h 2 IgE was 70.3 (12-242.5 kU/L). No correlations were observed between Tr1 and IgE values for peanut and Ara h2 when evaluating each time point.
CONCLUSIONS: Decreased peanut specific Tr1 Tregs could be detected as early as 6 weeks on POIT, These findings suggest that Tr1 cells may be an early marker of desensitization in subjects undergoing POIT.