MODULATION OF HLA-DR AND CD1A EXPRESSION ON HUMAN CORNEA WITH LOW-DOSE UVB IRRADIATION

Purpose. To evaluate the effects of low-dose UVB irradiation of HLA an d CD1a expression and the toxic effects of UVB on human corneas. Metho ds. 24 pairs of human corneas from 24 donors were studied. One cornea from each pair was randomly irradiated with UVB (100 mJ/cm(2)) after e nucleation. All corneas were then organ-cultured for 2, 7, 14 or 21 da ys. Endothelium was studied after enucleation and organ culture. Follo wing preservation, corneas were evaluated by means of light microscopy , morphometry and TEM. HLA and CD1a staining was performed using an im muno-alkaline-phosphatase technique. Results. Endothelial cell loss du ring organ culture averaged 9.1% in the UVB group and 9.2% in the cont rol group (NS). The number of rosette and reformation figures (p = 0.0 04) and the coefficient of variation (p = 0.014) were higher in the co ntrol group. Epithelial sloughing was more accentuated in the UVB grou p. We observed the same moderate ultrastructural injuries in both grou ps. In the epithelium, the average number of HLA-DR+ cells per field w as 0.12 in the UVB group and 0.42 in the control group (p = 0.035). In the stroma, these figures were respectively 1.04 and 1.34 (p = 0.026) . In the epithelium, the average number of CD1a + cells was respective ly 0.025 and 0.078 (p = 0.019). In the preservation mediums, the avera ge percentage of CD1a + cells was 0.07% in the UVB group and 0.27% in the control group (p = 0.014). Conclusions. Low-dose UVB (100 mJ/cm(2) ) decreases HLA-DR and CD1a expression of organ-cultured human corneas and induces moderate corneal injuries. Low-dose UVB might be useful f or preventing allograft rejection.