Role of IgG, IgA, and IgE antibodies in nasal polyp tissue: their relationships with eosinophilic infiltration and degranulation.

To confirm local production of IgE, and evaluate role of immunoglobulins on eosinophil activation in nasal polyp (NP) tissue, we measured IgG, IgA, secretory IgA(sIgA), total (tIgE) and specific IgE (sIgE) to Dermatophagoides pteronyssinus(DP) by ELISA in NP tissue homogenates from 51 subjects. They were classified according to skin reactivity to DP: group I, 15 highly atopic subjects; group II, 18 weakly atopic subjects; and group III, 18 non-atopic subjects. Eosinophil cationic protein (ECP) level was measured by CAP system. Highest level of DP-sIgE was noted in group I, followed by group II and III (p<0.05). Nine (60%) of group I and 4 (22%) of group II subjects had detectable level of DP-sIgE with no significant differences in IgA, sIgA, and IgG. All of NP tissue had eosinophilic infiltration with no significant difference in activated eosinophil count or ECP level among 3 groups. A significant correlation was noted between EG2+ cell count and tIgE (r=0.55, p<0.05), and DP-sIgE level (r=0.60, p<0.05). A significant correlation was also noted between ECP and IgG (r=0.51, p<0.05) and DP-sIgE level (r=0.47, p<0.05) with no significant correlation with IgA or sIgA. These results suggest that DP-sIgE was detectable in NP tissue from weakly atopic subjects as well as highly atopic subjects. IgG and sIgE may have potential roles in eosinophil degranulation in NP tissue.