The effect of type I and II interferons on human fetal retinal pigment epithelium-induced apoptosis in Jurkat T cells.

PURPOSE

To examine the regulatory effects of interferon (IFN)-alpha, IFN-gamma, transforming growth factor (TGF)-beta, and tumor necrosis factor (TNF)-alpha on human fetal retinal pigment epithelial (HFRPE) cell-induced apoptosis of human Jurkat T (Jkt) cells.

METHODS

Pure cultures of HFRPE cells were isolated. The cells were precultured with medium alone or with addition of IFN-alpha, IFN-gamma, TNF-alpha, or TGF-beta for 72 hours. Thereafter, HFRPE cells were extensively washed before they were cocultured jointly with Jkt cells (standard) or cultured alone for another 48 hours to accumulate conditioned medium that is collected and added as cell-free conditioned medium to Jkt cell cultures (supernatant). Jkt cells were cocultured under the two culture conditions for 48, 72, and 96 hours. The rate of apoptosis in Jkt T cells was determined with annexin V staining and flow cytometry.

RESULTS

Both IFN-alpha and -gamma upregulated HFRPE-induced apoptosis in Jkt T cells. However, the apoptosis induced by IFN-alpha-activated HFRPE cells was significant only in the absence of cell-cell contact (supernatant). The supernatant induced a higher rate of apoptosis in Jkt T cells when compared to the direct coculture of the cells. TGF-beta and TNF-alpha did not upregulate HFRPE-induced apoptosis in Jkt T cells.

CONCLUSIONS

These results indicate that type I and type II IFNs can upregulated HFRPE-induced apoptosis in Jkt T cells, IFN-gamma being the more effective cytokine. Neither, TGF-beta nor TNF-alpha upregulated the HFRPE-induced apoptosis in Jkt T cells. Although HFRPE-induced apoptosis was mediated in a cell-cell-contact-independent pathway, HFRPE cells may also express membrane-bound antiapoptotic molecules. These findings may help us to understand better the modulatory effects of pro- and anti-inflammatory cytokines on immune suppressive characteristics of RPE cells.