Aims: To investigate the levels of macrophage migration inhibitory factor (MIF) in intraocular fluids of uveitis patients, the capacity of intraocular infiltrating lymphocytes to produce MIF, and the correlation between MIF levels in the eye and intraocular inflammatory activity.
Methods: MIF levels were measured by enzyme linked immunosorbent assay (ELISA) using (1) aqueous humour (AH) of 12 uveitis patients and eight control patients with cataract, (2) vitreous fluid of 15 uveitis patients and eight control patients with idiopathic macular hole, and (3) culture supernatants of T cell clones (TCCs) established from intraocular fluids of uveitis patients. MIF expression on infiltrating cells was determined by a double staining immunofluorescence technique using a flow cytometry.
Results: Significant levels of MIF were detected from intraocular fluids of uveitis patients (4.0 (SD 3.0) ng/ml in AH and 16.5 (24.7) ng/ml in vitreous), whereas MIF levels in control groups were below the detectable levels. There was a significant correlation between MIF levels and vitreous inflammation (29.7 (30.0) ng/ml in active uveitis v 3.3 (2.6) ng/ml in inactive uveitis, p< 0.05). Significant levels of MIF were detected in culture supernatants of TCCs from ocular fluids of uveitis patients. MIF was expressed on infiltrating CD4+ lymphocytes from vitreous of uveitis patients.
Conclusion: Significant levels of MIF are present in intraocular fluids of patients with uveitis. Lymphocytes infiltrating in the eye are capable of producing MIF. MIF levels in vitreous fluid are correlated with vitreous inflammation activity. These data thus indicate that MIF in the eye has a significant role in the pathophysiology of ocular inflammation.