Frequency of anti-retinal antibodies in normal human serum.

BACKGROUND: Anti-retinal antibodies have been described in the context of autoimmune retinopathies and are often presumed to be pathogenic or disease associated. However, full characterization of patterns of anti-retinal antibody reactivity in normal human serum has been limited. The purpose of this work was to identify the profile of anti-retinal IgG antibodies in serum used as controls in laboratory testing.
METHODS: Normal human sera used in commercial diagnostic laboratories were tested for the presence of immunoreactivity against soluble human retinal proteins using Western blot analysis of fractionated soluble human retinal proteins. Reactivity was quantified using computerized densitometry, and the level of reactivity was standardized relative to a control positive serum with known reactivity against recoverin.
RESULTS: Some anti-retinal reactivity was observed in the majority of all tested normal sera. Reactivity against one to two protein bands was observed in 33%. Reactivity against five or more distinct bands was observed in 22%. There was a tendency for serum from women to react with three or more protein bands compared with serum from men.
CONCLUSIONS: The presence of anti-retinal antibodies is observed in a majority of normal control human sera, suggesting that identification of new candidate retinal autoantigens should be cautiously interpreted and subject to rigorous testing for disease association. Additional studies will aid development of a standardized protocol for validation of potential pathogenic seroreactivity.