Modulation of HLA antigen expression on conjunctival fibroblasts by gamma-interferon

We investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to induce class II HLA antigen expression on human conjunctival fibroblasts in cell culture. Cultures were established by explanting subconjunctival tissue from normal donor globes. Fibroblasts were treated with rhIFN-gamma at concentrations ranging from 1 to 500 units/ml and incubated for 1, 3 and 6 days. HLA antigens were detected by immunofluorescence using monoclonal antibodies in conjunction with flow cytometry. Class I antigen was identified using a monoclonal antibody directed against Beta-2 microglobulin (a component of the class I antigen complex). Class II histocompatibility antigens were detected using monoclonal antibodies specific for HLA-DR, HLA-DP and HLA-DQ. Class I antigen was present on all cells prior to induction and showed a trend toward increased density after treatment with rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, class II antigens were induced in a dose- and time-dependent fashion. HLA-DR expression was most sensitive to induction by rhIFN-gamma, followed by HLA-DP, and then HLA-DQ. The up-regulation of HLA class I antigen expression and the inducible expression of class II antigens following exposure to rhIFN-gamma suggest that conjunctival fibroblasts have the potential to participate in immunologic diseases of the external eye.