Porcine eye lens crystallins: antigenic similarity with human crystallins and tool for the detection of anti-crystallin antibodies

Background: The usual sources of antigenic material for investigations on circulating immunoglobulins with anti-lens crystallins specificity are saline extracts of human cataract lenses. This practice has a number of drawbacks, especially the possible antigenic alterations that may have occurred in cataract lenses. The aim of this investigation was to compare the antigenic properties of porcine eye lens crystallins and human crystallins, with regard to the possibility for an alternative source of antigenic material for detection of anti-crystallin antibodies in human sera. Methods: We produced rabbit antisera against saline extracts of human and porcine eye lenses. These sera were applied for the antigenic characterizations of the two extracts with indirect and absorption enzyme-linked immunosorbent assay. The two antigens were further compared by testing them against 30 human sera from cataract patients and 30 sera from blood donors. Results: The antibodies raised against human eye lens cross-reacted with antigens of the porcine lens. This finding was supported by the absorption experiments - the antigens of the porcine eye lens strongly inhibit the reactivity of the rabbit serum raised against human eye lens and vice versa. We established a significant positive correlation (Spearman, r=0.89, P<0.0001) between the reactivity of the tested sera against human and porcine lens extracts. Conclusion These data demonstrated a strong antigenic similarity between human and porcine lens crystallins, suggesting the appropriateness of the use of porcine lens extracts for the detection of humoral anti-lens autoimmune response in patients with eye diseases.