Is hypochlorous acid (HOCI) involved in age-related nuclear cataract?

Oxidative damage to lens proteins is associated with human age-related nuclear cataract and H 2O 2 has been implicated. As hypochlorous acid (HOCI) can be formed from chloride ions and H 2O 2 and many of the protein modifications observed in cataract are also noted following exposure of proteins to HOCI, age-related nuclear cataract lenses were examined for evidence of HOCI-mediated alterations. Method: Three techniques were employed using human lens samples: 1. staining with a HOP antibody that recognises HOCI-treated proteins, 2. myeloperoxidase assays and 3. measurement of chlorotyrosine in acid digests of the crystallins. Results: HOP staining was inconclusive, although cataract lenses appeared to stain more intensely than normals. No myeloperoxidase activity could be detected and neither mono-nor di-chlorotyrosine could be found in human lens proteins. Conclusions: On the basis of this study, no evidence was obtained to support a role for HOCl in age-related nuclear cataract.