PRODUCTION OF ANTI-LACTOFERRIN ANTIBODIES AND THEIR APPLICATION IN ANALYSIS OF THE TEAR FLUID IN HEALTH AND CORNEAL INJURIES

Abstract

Lactoferrin is a ubiquitous and multifunctional protein, which has antimicrobial and immunomodulatory activities. Lactoferrin plays an important role in the maintenance of ocular health. The aim of the study was to produce polyclonal antibodies against human lactoferrin in order to apply them in evaluation of lactoferrin levels in tear fluid collected from healthy eye and after corneal injury. Materials and methods. Affine chromatography on Protein A-sepharose was applied in order to isolate immunoglobulin G (IgG) fraction from the blood serum of lactoferrin-immunized rabbits. Each step of protein purification was monitored by denaturing gel electrophoresis (SDS-PAGE). Target antigen recognition by produced antibodies was established by western blot analysis with the use of diluted IgG fraction. Lactoferrin levels in the tear fluids collected from healthy individuals (n = 4) and patients with non-penetrating corneal injures (n = 6) were determined immunochemically with the use of purified antibodies. The results of western blot of lactoferrin levels in the tear fluids of healthy individuals and patients with corneal wounds were analysed using Mann-Whitney U-test. The difference between group mean values was considered significant at P<0.05. Results. Using affine chromatography on Protein A-sepharose, antibodies against human lactoferrin were purified as IgG fraction from blood serum of lactoferrin-immunized rabbits. Western blot analysis showed that obtained antibodies recognize the antigen as a 75-kDa band, which corresponds to the intact human lactoferrin polypeptide. The same major polypeptide band was visualized by western blot with enhanced chemiluminescence detection in the tear fluid samples. Densitometry analysis of 75-kDa lactoferrin band showed 3.2-fold decrease in lactoferrin level in the tear fluid samples obtained from patients with non-penetrating corneal traumas as compared with samples collected from healthy persons (P<0.05). Besides, tear fluid of patients with injured corneas contained large amounts of truncated lactoferrin immunoreactive polypeptides as well as high molecular weight bands, which could correspond to lactoferrin complexes with other proteins occurring during inflammation. Conclusions. According to our data, obtained anti-lactoferrin antibodies can be used as a valuable tool for development of advanced tests and procedures for diagnostics of eye diseases associated with the corneal lesions. Reduced lactoferrin concentration might represent a potential prognostic biomarker for diagnosis of ocular diseases including non-penetrating corneal injuries in a simple and non-invasive way.