Tear secretory IgA: evaluation of usefulness as a diagnostic marker in herpetic keratitis

In a South Indian study, an 'in-house' enzyme-linked immunosorbent assay (E LISA) was developed to evaluate the potential of herpes simplex virus (HSV) -specific tear secretory IgA (sIgA) in the diagnosis of herpes simplex kera titis (HSK). The presence of HSV-specific tear sIgA was found to be diagnos tic in 20.28% Of cases. The usefulness of the sIgA ELISA system was evaluat ed against HSV isolation, which is the 'gold standard' and HSV antigen dete ction, a more sensitive, commonly employed method. Analysis of HSV-specific IgG and IgM results showed their failure as reliable indicators of active or ongoing infection. Comparison of sIgA ELISA with culture as 'gold standa rd' showed its sensitivity, specificity, and positive and negative predicti ve values to be 60% (95% CI 36.4-80), 93.2% (95% CI 86.7-96.8), 60% (95% CI 36.4-80), and 93.2% (95% CI 86.7-96.8), respectively. This study is the fi rst report on the complete evaluation of the usefulness of tear anti-HSV sI gA in the laboratory diagnosis of HSK, taking into account both epithelial and stromal keratitis cases.