Soluble HLA-G molecules are released as HLA-G5 and not as soluble HLA-G1 isoforms in CSF of patients with relapsing–remitting Multiple Sclerosis

Cerebrospinal fluid (CSF) levels of sHLA-G (sHLA-G1/HLA-G5) molecules and their soluble isoforms HLA-G5 and sHLA-G1 were measured by ELISA procedures in 68 relapsing–remitting Multiple Sclerosis (RR MS) patients, in 67 patients with other inflammatory neurological disorders (OIND) and in 70 subjects with non-inflammatory neurological disorders (NIND). CSF concentrations of sHLA-G1/HLA-G5 and HLA-G5 were higher in RR MS than in OIND and NIND, and in Magnetic Resonance Imaging (MRI) inactive as compared to MRI active RR MS. Our results indicate that the potential implication of sHLA-G proteins in the resolution of MS intrathecal inflammatory response is probably due to HLA-G5 isoform.