FIGURE 2.

Rapid desensitization (DS) of mast cells (MCs) inhibits release of sFcεRI and it requires cumulative doses. Outline of the in vitro rapid DS protocol (A). A total of 1 × 10⁶/mL MCs (humanized murine bone marrow–ederived MCs) or MuKO (mFcεRIα^−/−) cells were loaded overnight with up to 10% allergic human serum in 200 μL (B, C). Percentage of β-hexosaminidase release (B) and total sFcεRI levels (C) were measured after DS with 0.5 μg/mL anti-hIgE. Razin Medium was used as control. A total of 1 × 10⁶/mL MCs were loaded overnight with 0.5 μg/mL anti-NP cIgE (D, E). Total sFcεRI levels were measured after a single-dose challenge or cumulative doses (10 pg/mL to 10 ng/mL NP-BSA) for 10 or 110 minutes. A single challenge with 10 ng/mL NP-BSA (Act) or 10 ng/mL BSA (Neg) was used as a control. Data represent mean ± SEM of n = 3–8 independent experiments. A 1-way ANOVA test plus Tukey’s multiple correction (B-E) was performed, where */δP < .05, **/δδP < .01, and ***P < .001 compared with Neg (B, C) or Act (D, E). δRepresents statistics between conditions in white bars (D). ANOVA, Analysis of variance; BSA, bovine serum albumin; nd, not detected; NP-BSA, 4-hydroxy-3-nitrophenylacetyl bovine serum albumin; SEM, standard error of the mean; sFcεRI, soluble FcεRI.