Detection of serum soluble HLA-G levels in patients with acute ischemic stroke: a pilot study

The aim of this study was to investigate the potential role of soluble Human Leukocyte Antigen-G (sHLA-G) molecules as biomarkers predicting outcome in acute ischemic stroke (AIS). Serum levels of total sHLA-G (sHLA-G1/HLA-G5) and its soluble isoforms sHLA-G1 and HLA-G5/G6 were measured by enzyme-linked immunosorbent assay (ELISA) in 92 AIS patients and healthy donors (HD). Incidence of hemorrhagic transformation (HT), size of final infarct volume (FIV) and clinical outcome at 3 months were recorded in AIS patients. Detectable serum levels of sHLA-G1/HLA-G5, HLA-G5/G6 and sHLA-G1 were present in a small proportion of AIS patients (26.1%, 17.4% and 16.3%, respectively) and HD (12.5%, 10.7% and 10.7%, respectively) and were more elevated in AIS patients without HT than in those with HT (p < 0.01; p < 0.05; p < 0.01, respectively). HT was less frequent (p < 0.01) in AIS patients with measurable serum concentrations of sHLA-G1/HLA-G5 and HLA-G5/G6. Serum levels of sHLA-G1/HLA-G5 and sHLA-G1 were inversely correlated to FIV (p < 0.02), whereas good outcome was more common (p < 0.01) in AIS patients with detectable serum concentrations of sHLA-G1/HLA-G5. Taken together, these findings suggest that total sHLA-G could exert a protective effect in a subset of AIS patients, irrespective of its soluble isoforms sHLA-G1 and HLA-G5/G6, and indicate that the prognostic value of serum levels of sHLA-G remains to be established.