Human leukocyte antigen-class II-positive human corneal epithelial cells activate allogeneic T cells.

PURPOSE To achieve a better understanding of the mechanism of corneal immune diseases, including corneal allograft rejection, the authors examined the potential of human corneal epithelial (HCE) cells to activate allogeneic T lymphocytes. METHODS The mixed lymphocyte-HCE cell reaction (MLCER) was performed as follows: HCE cells from primary cultures, with or without treatment with interferon-gamma (IFN-gamma), were treated with mitomycin C and then mixed with peripheral blood lymphocytes (PBL) from normal volunteers. Triplicate cultures were incubated for 7 days. Interleukin-1-alpha (IL-1-alpha) was added to some cultures to examine its effect on MLCER: The lymphocyte responses were measured by 3H-thymidine uptake for the last 18 hours of incubation in MLCER: RESULTS IFN-gamma-treated, HLA-class-II-bearing HCE cells stimulated allogenic lymphocytes, whereas IFN-gamma nontreated, class-II-negative HCE cells did not. The stimulation by IFN-gamma-treated HCE cells was blocked by anti-HLA class II monoclonal antibody. In addition, exogenous IL-1-alpha reduced the lymphocyte response in MLCER: This effort was inhibited by indomethacin. CONCLUSIONS This study demonstrates that HLA-class-II-bearing HCE cells can activate allogeneic PBL by a major histocompatibility complex class II-dependent mechanism. In addition, HCE cells may regulate immune reactions, probably through prostaglandin production caused by IL-1.