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Abstract
PURPOSE: To establish a correlation between the presence of a 36 kDa protein in the blood of patients with pars planitis and to characterize and purify this protein. METHODS: Blood samples were obtained from patients with pars planitis and other types of uveitis and from various controls. Samples were treated with polyethelene glycol and protein A and were analyzed on 10% SDS-PAGE for the presence of a 36 kDa protein. Quantitative estimation of the level of this protein was determined by densitometric tracing of the stained gels. Polyclonal antibodies were raised by immunizing New Zealand White rabbits with a mixture of the gel fragment containing the 36 kDa protein (p-36) and complete Freund's adjuvant. These antibodies were used in the immunoaffinity purification of this protein. RESULTS: The levels of p-36 were sixfold to eightfold higher in 81% of the patients with active pars planitis than in controls (P < 0.05). Furthermore, the levels of this protein correlated with disease activity. A partial amino terminal sequence analysis revealed that p-36 may be a novel protein. It has been purified from the patient's blood using affinity chromatography. CONCLUSIONS: A 36 kDa protein (p-36) is found in elevated concentrations in the blood of many patients with active pars planitis. Its putative role in the etiopathogenesis of pars planitis is unknown.