Viral antibodies in normal tears

Viruses are a common cause of eye infection. The local mucosal response, with production of antibodies released into tears, is believed to provide an important immune defense against these agents. However very little information exists on the viral specificity of normal tear immunoglobulins. In this study we obtained tears, parotid saliva and serum from 40 normal subjects without eye disease. Samples were examined by enzyme linked immunosorbent assay (ELISA) for antibodies to seven common viruses which invade mucosa: cytomegalovirus (CMV), Epstein Barr (EBV), herpes simplex type I (HSVI), measles, mumps, rubella and varicella zoster virus (VZV). The majority of normal tears contained antibodies to HSVI (73%) and EBV (65%), occasionally to mumps (30%), rubella (30%), and VZV (20%), and rarely to CMV (5%). Tear viral antibodies were mainly IgA class, but it was not unusual for find IgG antibodies to HSVI, VZV, rubella and measles. Tear and parotid saliva immunoglobulins from the same individual had entirely different viral reactivity. In most cases tear viral antibodies were reflected in serum viral antibodies, although the immunoglobulin class might differ. However, 15% of normal tears had antibodies to HSVI without detectable serum antibodies. From this study we conclude that normal tear immunoglobulins contain antibodies to common viruses, in particular to HSVI and EBV. These tear antibodies are mainly IgA, but can consist of IgG. Viral antibodies in tears are independent of the antibodies present in parotid saliva, suggesting that there is preferential homing of committed B lymphocytes to different mucosal surfaces, Finally, the finding of tear antibodies to HSVI in the absence of detectable serum antibodies suggests that the ocular surface may be the initial infection site for this virus in some healthy normal subjects.