CXCL8 and major depressive disorder: The aim of this study was to assess changes in the concentration of IL-1β, IL-4, IL-8 and IL-10 among patients with mild depression (MD), moderate depression (MOD), severe depression (SeD), MD and PTSD (MD + PTSD), MOD and PTSD (MOD + PTSD), SeD and PTSD (SeD + PTSD), and with PTSD alone, in order to find potential markers of altered stress reactivity associated with both depression and PTSD.