S, a link between CD40 and microglia has been established. Upregulation of CD40 expression has been detected on microglia of HIV-1-infected brain tissues [28]. CD40L was also shown to potentiate the ability of HIV-1 Tat to activate monocytes and microglia leading to the overproduction of inflammatory proteins such as cytokines and chemokines [122]. Furthermore HAART is unable to modulate blood bra