Purpose: To investigate the role of specific secretary IgA antibodies on lipopolysaccharide (LPS-sIgA) and exotoxin A (ETA-sIgA) in tear fluid produced by immunoresponse to P. aeruginosa.
Subjects and methods: Subjects were divided into 3 groups; 41 eyes of 41 normal volunteers without a history of using contact lenses (CL) as controls, 32 eyes of 32 CL users without adverse events as a healthy CL wearer group (CL group), and 12 eyes of 12 patients with CL-related corneal ulcers from which P. aeruginosa was isolated (ulcer group). Tear fluid was obtained using filter paper, and the concentration of LPS-sIgA and ETA-sIgA in samples was determined using enzyme-linked immunosorbent assay (ELISA).
Results: The lower limit of concentration for LPS-sIgA and ETA-sIgA was 1.24 and 1.24 (U/mL), respectively. The positive eyes which exceeded this lower limit in LPS-sIgA were 17 of 22 eyes in the control group (median concentration 2.00 U/ml, range 1.28 to 7.20), 15 of 25 eyes in the CL group (median 1.76 U/ml, range 1.24 to 6.92) and 1 of 12 eyes in the ulcer group (1.80 U/ml). The number of eyes which exceeded the lower limit in ETA-sIgA was 36 of 41 eyes in the control group (median concentration 6.56 U/ml, range 1.36 to 182), 28 of 32 eyes in the CL group (median 5.40 U/ml, range 1.56 to 29.20) and 5 of 12 eyes in the ulcer group (median 1.72 U/ml, range 1.40 to 2.16). There was no significant difference in LPS-sIgA and ETA-sIgA between the control group and the CL group, but they were significantly lower in the ulcer group than in the control group (p<0.01, Steel's test).
Conclusion: Tear fluid in normal, healthy CL wearers contains LPS-sIgA and ETA-sIgA which acts as a barrier to P. aeruginosa infectious keratitis.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 117: 996-1003, 2013.