CD40LG and HIV-associated neurocognitive disorder: Consistent with this notion, we have previously shown that levels of the inflammatory mediator soluble CD40 ligand (sCD40L) are elevated in the plasma and cerebrospinal fluid (CSF) of HIV infected, cognitively impaired individuals, and that excess sCD40L can contribute to blood brain barrier (BBB) permeability in vivo, thereby signifying the importance of this inflammatory mediator in the pathogenesis of HAND.