Whereas some studies reported higher LPS-stimulated IL-6 production [22] or increased LPS/PHA-induced production of IL-6 and TNF-α [23] in individuals with PTSD, other studies showed no group differences with respect to PHA-induced interferon (IFN)-γ [24] or LPS-induced TNF-α production [22]. Here, TNF is linked to post-traumatic stress disorder.