Increased levels of serum CX3CL1 are reported in patients with multiple sclerosis [39, 44], traumatic brain injury [45], and human immunodeficiency virus (HIV) with CNS complications [46], but increased levels of serum CX3CL1 are not observed in patients with Guillain-Barré Syndrome and viral and bacterial meningitis [44]. Here, CX3CL1 is linked to bacterial meningitis.