Hemozoin “knobs” in Opisthorchis felineus infected liver

BACKGROUND: Hemozoin is the pigment produced by some blood-feeding parasites. It demonstrates high diagnostic and therapeutic potential. In this work the formation of co-called hemozoin “knobs” – the bile duct ectasia filled up by hemozoin pigment - in Opisthorhis felineus infected hamster liver has been observed. METHODS: The O. felineus infected liver was examined by histological analysis and magnetic resonance imaging (MRI). The pigment hemozoin was identified by Fourier transform infrared spectroscopy and high resolution electrospray ionization mass spectrometry analysis. Hemozoin crystals were characterised by high resolution transmission electron microscopy. RESULTS: Hemozoin crystals produced by O. felineus have average length 403 nm and the length-to-width ratio equals 2.0. The regurgitation of hemozoin from parasitic fluke during infection leads to formation of bile duct ectasia. The active release of hemozoin from O. felineus during in vitro incubation has also been evidenced. It has been shown that the hemozoin knobs can be detected by magnetic resonance imaging. CONCLUSIONS: In the paper for the first time the characterisation of hemozoin pigment extracted from liver fluke O. felineus has been conducted. The role of hemozoin in the modification of immune response by opisthorchiasis is assumed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-015-1061-5) contains supplementary material, which is available to authorized users.