Superantigen presentation by human retinal pigment epithelial cells to T cells is dependent on CD2-CD58 and CD18-CD54 molecule interactions.

Human retinal pigment epithelial (RPE) cells are capable of presenting bacterial superantigens (SAg) to T cells in vitro by ligation of MHC class II molecules on RPE cells with the T cell receptor. The purpose of this study was to evaluate the involvement of adhesion molecules in presentation of SAg. Cultured human fetal and adult RPE cells were treated with interferon-γ (IFN-γ, 500Uml−1 for 72hr) and afterwards pulsed with the SAg staphylococcal enterotoxin A (SEA, 500ngml−1 for 2hr) followed by coculture with freshly obtained T cells isolated from peripheral blood. Proliferation was measured by 3H-thymidine incorporation assay. In selected experiments, either RPE or T cells were pre-treated with blocking antibodies specific for cell surface molecules. For comparison, dendritic cells were used as superantigen presenting cells for T cells. This study showed that presentation of SEA by RPE cells to resting T cells was dependent on the presence of the molecules CD2, CD58 and CD18, CD54. The cycling status of T cells was decisive, thus resting T cells but not activated T cells were capable to proliferate in response to SEA presentation. Proliferation of T cells induced by adult RPE cells was comparable to the proliferation induced by dendritic cells at concentrations of SAg above 100ngml−1, but at concentrations of SAg below 10ngml−1 the response was significantly lower for SAg presented by RPE cells compared to dendritic cells. The results demonstrate that CD2–CD58 and CD18–CD54 interactions are critical for SAg presentation by RPE cells to T cells. The findings thus suggest that also presentation of peptides to resting T cells by RPE cells may be dependent upon these interactions.