T-cell repertoire of normal, rejected, and pathological corneas: phenotype and function.

The specific immune mechanisms of corneal graft rejection are not completely understood. Recently, the technique of growing T-cell lines from rejected allografts using recombinant IL-2 has enabled the cells involved in allograft rejection to be recognized. In the present study, this method was applied for the extraction and propagation of T lymphocytes from rejected, normal, and diseased corneas. T-cell lines could successfully be grown from rejected and normal corneas, but not from corneas with keratoconus or pseudophakic bullous keratopathy. The phenotypic repertoire of the grown cells was studied by FACS scan analysis. Rejected corneas were invaded by a mixture of activated CD4+ and CD8+ T-cell lines, with one population being predominant. In normal corneas only activated CD8+ cells with cytotoxic function were cultured. No cells were obtained from diseased corneas. The in vitro function of cell lines was assessed by primed lymphocyte testing. The present study shows that the technique of propagating invading T-cell lines from organ grafts can be applied to human corneas, offering a new approach to understanding the immunological mechanisms occurring inside this immune tissue.

[T-lymphocyte population in the normal human cornea]. / Population T-lymphocytaire de la cornée humaine normale.

T-lymphocytes of the normal human cornea (10 donors) were studied from corneal fragments cultured in IL-2 medium. Their phenotypic repertoire was performed by FACS analysis using the following monoclonal antibodies: CD3, CD19, CD4, CD29, CD18, CD16, CD56, CD25, TCR alpha/beta, TCR alpha/delta. Functional analysis was done by proliferation assays (PLT). T cell growth was more often obtained from peripheral (n = 7/10) than central corneal parts (n = 3/10). Most of the cultured cells carried the CD8 marker, were activated (HLA-DR+) and had a cytotoxic function (CD 18+). All their T cell-receptors were alpha/beta type. No NK cells could be detected. No specific proliferation was observed when tested on a panel of HLA typed presenting cells. This study demonstrated activated T-lymphocytes in the normal human cornea. These activated, cytotoxic CD8+ lymphocytes could participate in the particular immunological characteristics of the eye.