Altered Natural Killer cells response to herpesvirus infection in Multiple Sclerosis involves KIR2DL2 expression

The role of Herpesviruses as potential triggers of Multiple Sclerosis (MS) is still debated. Peripheral blood mononuclear cells from MS patients and controls were treated with CpG sequences and infected in vitro with HSV-1. Samples were analysed for viral yield, TLR9 pathways, cytokine secretion, NK cell activation and killer immunoglobulin-like receptors (KIR) expression. CpG treatment promoted an unexpected sensitivity to herpesvirus infection in a subset of MS patients: TLR9 pathways did not show defects while NK cells presented decreased degranulation and cytotoxicity and up-regulated the inhibitory KIR2DL2 receptor. CpG treatment on purified NK cells affected directly KIR2DL2 modulation and cell activation. These preliminary data suggest potential implications for viral pathogenesis of MS.