Induction of experimental autoimmune keratitis by adoptive transfer of human corneal antigen-specific T-cell line.

PURPOSE

To establish a permanent human corneal antigen (HuCOAg)-specific T-cell line and to determine whether line cells are capable of inducing inflammatory keratitis by adoptive transfer.

METHODS

Lymphoid cells harvested from HuCOAg-immunized Lewis rats were expanded to a permanent T-cell line by repetitive cycles of restimulation with HuCOAg and irradiated antigen-presenting cells and propagation in interleukin 2-containing medium. The phenotype and epitope specificity of the line cells were determined. Adoptive transfer was performed after seven cycles by intraperitoneal injection of activated T cells into irradiated recipient rats.

RESULTS

A panel of 11 overlapping synthetic HuCOAg peptides to identify T-cell epitopes recognized by the line cells was used. The cells responded selectively to a synthetic peptide containing an immunodominant epitope of HuCOAg (peptides 69-83). Line cells bore the surface phenotype of the T-helper/inducer marker (W 3/25(+) or CD4(+)). Intraperitoneal inoculation of naive rats with 5 x 10(7) activated line cells led to maximal clinical signs of stromal keratitis 7 to 9 days after transfer, characterized by corneal haze, conjunctival and episcleral injection, corneal infiltrates, and neovascularization. Histopathologic examination of the tissues revealed numerous lymphocytes and macrophages and some polymorphonuclear leukocytes along with neovascularization. The pathologic lesions were confined to the peripheral corneal stroma. Immunohistochemical studies demonstrated that the overwhelming majority of the inflammatory cells were CD4(+) T lymphocytes and macrophages; an upregulation of major histocompatibility complex class II antigen expression was also noted.

CONCLUSIONS

A long-term, rat T-cell line of CD4(+) phenotype specific for HuCOAg that can induce autoimmune keratitis by adoptive transfer of the line cells to naive syngeneic recipients is described. With the development of this cell line, the mechanisms by which T cells exert their immunopathologic effects in experimental autoimmune keratitis models can be studied.