Effect of Fas and Fas ligand deficiency in resistance of C57BL/6 mice to HSV-1 keratitis and chorioretinitis

PURPOSE. To investigate the effect of Fas and Fas ligand (FasL) deficiency on the development of herpes stromal keratitis and on the von Szily model of herpes retinitis in C57BL/6 mice, which are ordinarily resistant to development of both of these herpetic diseases. METHODS. Anterior chamber inoculation of the right eye of each mouse with various titers of H.-1. (KOS strain) was performed. Both eyes of each mouse were enucleated on postinoculation day 15 and processed for histopathologic examination. HSV-1 was inoculated into one cornea of other mice, and the severity of stromal keratitis was scored. RESULTS. Contralateral destructive chorioretinitis developed in susceptible Balb/cByj mice (19/23); ipsilateral chorioretinitis did not occur (0/23). Stromal keratitis developed in susceptible C.AL-20 mice (15/16). None of the C57BL/6 (0/10 for keratitis or 0/20 for retinitis) developed inflammation. Neither did B6.SMN.C3H.gld (FasL deficient; 0/12 or 0/28) or B6.MRL.lpr (Fas deficient; 0/11 or 0/34) mice (keratitis or contralateral chorioretinitis). Minimal scattering of inflammatory, cells in the contralateral retina but not destructive chorioretinitis was observed in two C57BL/6, three B6.SMN.C3H.gld, and five B6.MRL.lpr mice. Few inflammatory, cells were also found in the ipsilateral vitreous and vitreoretinal interface (but not destructive chorioretinitis) of all C57BL/6, two gld, and three lpr mice. CONCLUSIONS. Immune dysregulation secondary to deficiency in Fas or FasL system does not influence the resistance of the C57BL/6 mice to develop herpes simplex keratitis or destructive herpes simplex chorioretinitis.