The
protein profile of serum samples from patients with
amoebic liver abscess (ALA) was compared to those of normal individuals to determine their expression levels and to identify potential surrogate disease markers. Serum samples were resolved by two dimensional electrophoresis (2-DE) followed by image analysis. The up and down-regulated
protein spots were excised from the
gels and analysed by MS/MS. The concentration of three clusters of
proteins i.e.
haptoglobin (HP), α1-antitrypsin (AAT) and
transferrin in serum samples of ALA patients and healthy controls were compared using competitive ELISA. In addition, serum concentrations of HP and
transferrin in samples of patients with ALA and
pyogenic liver abscess (PLA) were also compared. The results of the
protein 2-DE expression analysis showed that HP cluster, AAT cluster, one spot each from unknown spots no. 1 and 2 were significantly up-regulated and
transferrin cluster was significantly down-regulated in ALA patients' sera (p<0.05). The MS/MS analysis identified the unknown
protein spot no.1 as human transcript and
haptoglobin and spot no. 2 as
albumin. Competitive ELISA which compared concentrations of selected
proteins in sera of ALA and healthy controls verified the up-regulated expression (p<0.05) of HP and the down-regulated expression (p<0.01) of
transferrin in the former, while there was no significant difference in AAT expression (p> 0.05). However, when ALA and PLA samples were compared, competitive ELISA showed significant increased concentration of HP (p<0.05) while
transferrin levels were not different. In conclusion, this study showed that HP is a potential surrogate disease marker for ALA.