Evaluation of total and allergen-specific secretory IgA in tears of allergic conjunctival disease patients

To investigate the variations in total secretory IgA (sIgA) and house dust mite (HDM)-specific sIgA antibodies in tears of patients with allergic conjunctival disease (ACD). The subjects comprised 40 patients (40 eyes) with ACD and 21 healthy individuals as a control. Patients with ACD comprised three groups: 16 patients (16 eyes) with perennial allergic conjunctivitis (PAC group), 11 patients (11 eyes) with atopic keratoconjunctivitis (AKC group), and 13 patients (13 eyes) with vernal keratoconjunctivitis (VKC group). Tear samples were taken by the Schirmer I method using filter paper. Tear samples were eluted and analyzed for total sIgA and HDM-specific sIgA antibodies in tears by enzyme-linked immunosorbent assay. The mean (+/-SD) value of total sIgA in tears in the control, PAC, AKC, and VKC groups was 1446.7 +/- 1220.1, 706.8 +/- 567.2, 440.4 +/- 151.8, and 460.8 +/- 340.6 microg/ml, respectively. Total sIgA values were significantly lower in the VKC group than in the control group. We defined the HDM index as the ratio of HDM-specific sIgA to total sIgA. The HDM index in the VKC (P < 0.001), AKC (P < 0.001), and PAC (P < 0.001) groups was significantly higher compared with those in the control group. Low levels of total sIgA and high levels of HDM-specific sIgA indicate a local pathogenic factor in ACD.