Reactivity and sensitivity of mast cell degranulation and Prostaglandin D2 synthesis increase with increasing affinity of IgE for allergen.
Mast cell reactivity was threefold higher with high affinity IgE clones (65%; IQR = 47 – 80) than with low affinity clones (20%; IQR = 12 – 25, p=0.0081) (figure 1A). Mast cell sensitivity (EC50) decreased 12.850-fold from 0.07 pg/ml (IQR = 0.02 – 7.2) Der p 2 allergen with high affinity clones to 900 pg/ml (IQR = 0.3 – 1.1) Der p 2 allergen when low affinity clones were used for sensitization (p=0.0395). Release of prostaglandin D2 assessed at 0, 3, 6 and 24 hours by EIA developed with significance for time (p<0.007) and affinity (p=0.0437) compared with baseline (n=3, Figure 1B). The release of PGD2 and its metabolites PGJ2, delta-12-PGJ2 and 15-deoxy-delta-12,14-PGJ2 was validated by mass spectrometry in a separate cell line (Figure 1, c-f). Four-fold more PGD2 was synthesized with high affinity IgE than with low affinity IgE activation after 3 (p=0.0024) and 6 (p=0.0188) hours (n=4).