Intravitreal Levels of Human Complement Factor H (CFH)

Abstract

Purpose: : A common haplotype in the gene for the regulator of the alternative pathway of complement CFH has been linked to individual predisposition to age–related macular degeneration. CFH is primarily synthesised in the liver. Recently, PCR–analysis revealed CFH transcripts in human RPE cells. Intravitreally, presence of complement molecules MCP, DAF and CD59 have been described. In this study we measured vitreous levels of CFH in patients with and without dysfunction of the inner blood retinal barrier.

Methods: : Vitreous samples from patients undergoing pars plana vitrectomy were obtained under air pressurization of the globe. Quantitative analysis of intravitreal CFH levels was performed by ELISA using CFH specific monoclonal antibodies. Intravitreal levels were correlated to serum levels of CFH.

Results: : Five patients were tested. Four underwent surgery for epiretinal gliosis, one patient had proliferative diabetic retinopathy with retinal traction (PDR) without haemorrhage. Mean serum levels of patients CFH were 795.65 µg/ml. Mean intravitreal levels were 3.08 µg/ml (range 1.54–3.45µg/ml) in patients with epiretinal gliosis and 33.3 µg/ml in the case with PDR.

Conclusions: : Intravitreal levels of CFH are 256 times lower compared to serum. However, in a case of outer blood–retina barrier dysfunction (PDR) we found 10 times higher CFH levels compared to eyes with functional blood–retina barrier. AS PCR analysis has shown that CFH transcripts in RPE cells are comparable to liver cells, we expected higher intraocular levels of CFH. Presumably CFH is primarily released to the choriocapillaris.

Keywords: age-related macular degeneration • pathology: human • immunohistochemistry