Aim: Homocitrulline (Hcit) is a modified amino acid originated by carbamylation of lysine residues and it is considered a potential biomarker in inflammatory diseases. Behçet's disease (BD) is an autoinflammatory disease, the diagnosis of the disease is based on clinical findings. Our aim was to investigate Hcit levels in inactive, active patients with BD and healthy subjects and to contribute to the elucidation of the relationship between Hcit levels and pathogenesis and activation of BD.

Material and Methods: The study included 26 active, 34 inactive patients with BD, and 30 healthy volunteers. Serum Hcit and lysine levels were quantified using the tandem mass spectrometric method (LC-MS/MS). Serum high sensitivity-CRP (hs-CRP) levels were quantified by IMMAGE 800 system (Beckman Coulter, Brea, USA). Various hematological and biochemical parameters of patients were quantified by Beckman Coulter LH 780 and Beckman-Coulter AU 5800, respectively.

Results: Hcit/lysine ratio (μmol Hcit/mol lysine) was statistically significantly higher in patients with BD [844.6(453.8-5975.4)] than healthy controls [334.9(117-509.3), (p<0.002)] and was remarkably higher in the active group [1307.0(453.8-5975.4)] compared to the inactive group [666.5(462.6-1777.2), p=0.005]. Moreover, Hcit/lysine ratios were positively correlate with hs-CRP (r= 0.353, p=<0.001).

Conclusion: Our findings showed that serum Hcit levels were high in patients with BD, and serum Hcit levels were correlated with the inflammatory load. Increased Hcit concentrations may be related to the autoinflammatory process and vascular damage in BD.