Figure 1.
Expression of FcεRI on cDC correlates with serum IgE but not with subject's age.
(A) Gating strategy used to identify expression of FcεRI and IgE on cDC and pDC. Cells were gated on scatter (R1) and lack of expression of CD19 (R2, PerCP negative). Those events that satisfied both of these criteria were examined for expression of ILT7 (R3, PE positive) versus CD1c (R4, APC positive). Cells that were CD19−ILT7+CD1c− were considered pDC and CD19−ILT7−CD1c+ were considered cDC. The expression of FcεRI (left histograms, FITC positive) or IgE (right histograms, FITC positive) on these cells was then determined and compared to an appropriate isotype control. (B) Expression of FcεRI on peripheral blood cDC was determined by flow cytometry and compared to subject's age or (C) serum IgE level. Data are presented as fold MFI FcεRI versus age in months (B) or serum IgE in kU/L (C), with non-sensitized subjects (n = 15) in circles and sensitized subjects (n = 12) in x's. Sensitization was defined as having at least one positive allergen specific IgE by ImmunoCAP.
Table 1.
Subject Characteristics.
Table 2.
Comparison of Sensitized and Non-Sensitized Children for Dendritic Cell Expression of IgE and FcεRI.
Figure 2.
Correlation of cDC expression of FcεRI with IgE.
Expression of FcεRI and IgE on the surface of cDC was determined by flow cytometry. (A) Data are presented as fold MFI FcεRI versus fold MFI IgE expression, with non-sensitized subjects (n = 15) in red circles and sensitized subjects (n = 12) in black x's. Note the difference in the slope of the fitted lines (non-sensitized subjects in red dotted line; sensitized subjects in black solid line) above and below a fold MFI IgE of 12, suggesting that there is differential regulation of FcεRI on cDC around this level of cell bound IgE. For all subjects the data was fit with the following cubic equation (blue line): Ln(cDC FcεRI) = 2.26+0.72*ln(cDC IgE)-0.43*ln(cDC IgE)2+0.082*ln(cDC IgE)3); r = 0.86; p = 0.045. For equations based on sensitization status, see Table 3. (B) Expression of cell bound IgE on cDC compared with serum (free) IgE levels. Data are presented as in (A) with fold MFI IgE expression versus serum IgE (kU/L). Note that a cell bound IgE fold MFI of 12 correlates with a serum IgE of around 38 (based on statistical fitting of the curve, this value could range between 34 and 42 kU/L).
Table 3.
Sensitization status regression models with significant Pearson correlations.
Figure 3.
Expression of FcεRI on pDC does not correlate with serum IgE or age of subject.
Expression of FcεRI on peripheral blood pDC was determined by flow cytometry and compared to subject's age (panel A) and serum IgE level (panel B). Data are presented as in Figure 1.