Conjunctival inflammation induces Langerhans cell migration into the cornea

The virtual absence of Langerhans cells (LC) in donor or recipient corneal epithelium is known to be an important factor in the acceptance of orthotopic corneal allografts. Though it is well known that various types of stimulation to the cornea induce LC migration into the corneal epithelium, resulting in poor graft survival, the influence of conjunctival inflammation on LC migration into the cornea has not been elucidated. Therefore we examined whether LCs migrate into the cornea in the presence of conjunctival inflammation.

Sixteen BALB/c mice were divided into four groups. Group A: 4 mice with corneal inflammation induced by two 9-0 silk interrupted sutures in the central cornea (positive control); Group B: 4 mice with conjunctival inflammation induced by two 9-0 silk interrupted sutures in the temporal and nasal bulbar conjunctiva 1 mm from the limbus; Group C: 4 mice with conjunctival inflammation by two 10-0 nylon interrupted sutures in the temporal and nasal bulbar conjunctiva 1 mm from the limbus; and Group N: 4 mice with no inflammation (untreated, naive control). Fourteen days after suturing, the mice were sacrificed and LCs migrated into the corneal epithelium were counted by immunofluorescence assay using anti-Ia antibody.

In Group A, Ia(+) cells in the cornea totaled 29.4 +/- 3.8 cells/mm(2); in Group B, 7.9 +/- 1.2 cells/mm(2); in Group C, 7.8 +/- 0.7 cells/mm(2); and in Group N, 1. 6 +/- 0.5 cells/mm(2). Significantly greater numbers of Ia(+) cells were detected in Groups A, B and C than in Group N (p < 0.005).

Conjunctival inflammation caused by sutures in the bulbar conjunctiva induced LC migration into the cornea. These results indicate that conjunctival inflammation influences the corneal immunological environment, and may affect the fate of orthotopic corneal allografts.