ORBITAL TISSUE-DERIVED T-LYMPHOCYTES FROM PATIENTS WITH GRAVES OPHTHALMOPATHY RECOGNIZE AUTOLOGOUS ORBITAL ANTIGENS

Lymphocytic and other mononuclear cell infiltration of the retrobulbar space is observed in Graves' ophthalmopathy (GO). We investigated the antigenic character of orbital adipose/connective tissue and muscle f rom 21 euthyroid patients with severe GO after orbital surgery. Orbita l tissue proteins were separated and recovered in soluble form by mean s of an electroelution technique. Twenty-two protein fractions, identi fied according to their molecular mass ranges, were used as antigens f or orbital tissue-derived and peripheral blood T lymphocytes. Seventee n T cell lines from 6 patients were established from in vivo activated orbital T cells using interleukin-2 and anti-CD3 antibodies. T Cell p roliferation was measured as [H-3]thymidine uptake. When screened for their reactivity to autologous adipose/connective tissue proteins, all T cell lines responded significantly to protein fractions 6-10 kDa [s timulation index (SI)=32.9+/-9.8 (mean+/-SE)] and 19-26 kDa (17+/-5), but not to tuberculin, which was used as a control. Phenotypic analysi s of 1D orbital T cell lines indicated that 6 lines consisted predomin antly of CD4(+) cells. Incubation of a representative T cell line with allogeneic orbital protein fractions induced a very low response to p rotein fraction 19-26 kDa, but not to other fractions. Thyroid protein fraction 6-10 kDa also induced the proliferation of orbital T cell li nes. Incubation of peripheral blood mononuclear cells with autologous orbital protein fractions gave similar results; positive responses to 6-10 and 19-26 kDa fractions were observed with orbital tissue from 12 of 14 patients (mean SI=22+/-5.9 and 6.3+/-1.7, respectively), and po sitive responses were observed with orbital tissue from 3 of 4 patient s to eye muscle fractions 6-10 and 19-26 kDa (13.8+/-6.9 and 6+/-2, re spectively). When proteins from cultured orbital fibroblasts were used as antigens, autologous peripheral blood mononuclear cells from the 7 of the 9 patients tested responded to these 2 fractions (15.2+/-6.9 a nd 6.8+/-2.4, respectively), whereas a response to cultured orbital my oblasts was observed with the 19-26 kDa fraction only (SI=8). Positive responses to abdominal adipose or muscle proteins, as controls, were not found. The demonstration of sensitized, orbital tissue-specific, T lymphocytes in the peripheral blood and orbit from patients with GO p rovides evidence for a role of cellular immunity in the pathogenesis o f this eye disorder.