Complement Factor P in choroidal neovascular membranes of patients with age-related macular degeneration.

Abstract

To evaluate whether complement Factor P (properdin) was present in surgically removed choroidal neovascular membranes of patients with age-related macular degeneration (AMD) and to investigate whether associated pre- and postoperative clinical characteristics can be correlated. The study population consisted of 26 AMD patients (26 eyes) with the exclusion criterion of prior treatment of the choroidal neovascular membranes. Factor P was detected immunocytochemically on paraffin sections (7 microm) by a polyclonal rabbit antihuman antibody. Eleven of 22 assessable membranes showed a positive reaction for Factor P. The average percentage of Factor P-positive cells per membrane ranged from 0.65% to 4.09%. The duration of visual loss was significantly longer (8.6 +/- 2.7 vs. 3.9 +/- 0.8 months), and the size of postoperative measured area of atrophic retinal pigment epithelium was larger (27.6 +/- 7.6 vs. 15.0 +/- 6.9 mm2) in patients with Factor P-positive membranes compared with Factor P-negative ones. Factor P was expressed in 50% of choroidal neovascular membranes of patients with AMD. The group with Factor P-positive membranes differed significantly from the Factor P-negative group in key clinical outcomes. Additional studies need to investigate the role of Factor P in the development of AMD for potential therapeutic intervention.