Histological and immunopathological analysis of T-cells mediating murine HSV-1 keratitis.

BACKGROUND: Thymus-derived lymphocytes play a critical role in the development of herpes simplex keratitis (HSK). T-cell subsets defined by their expression of various T-cell receptor (TCR) V beta segments were studied following corneal HSV-1 infection (p.i.).
METHODS: Conjunctiva, corneal limbus and corneal stroma of two inbred BALB/c congenic mouse strains which differ only in the gene products closely linked to the Igh-1 locus on chromosome 12 were analyzed.
RESULTS: While C.B-17 mice (Igh-1b) were resistant to HSK, C.AL-20 mice (Igh-1d) clinically developed severe necrotizing keratitis by day 11 p.i. The corneal stroma of C.B-17 mice remained clear, while it was increasingly infiltrated by mononuclear cells and neutrophils in C.AL-20 mice by day 11 p.i. In C.B-17 mice, Thy1.2+ cells were found in the conjunctiva between days 2 to 4 p.i., and subsequently decreased. Only a few Thy1.2+ cells were found in the limbus, and no such cells were found in the stroma. In contrast, in C.AL-20 mice the numbers of Thy1.2+ cells (activated CD4+, V beta 8+ T cells) profoundly increased in the conjunctiva by day 4 p.i. These cells infiltrated the limbus between days 7 and 11 p.i. and eventually entered the stromal tissue by day 11 p.i.
CONCLUSIONS: Our data suggest that the HSV-1-induced corneal tissue destruction is mediated by mononuclear cells and neutrophils and that these cells are probably attracted into the cornea by cytokines elaborated by activated CD4+, V beta 8+ T cells.