CD4 and serum lipopolysaccharide activity: In an endotoxemia model in humans, it has been demonstrated that as early as 3 hours after LPS inoculation, whole populations of CD4+ and CD8+ T cells decline, and the pro-inflammatory T-helper cells transiently lose their capacity to produce IL-2, TNF-α, as well as IFN-γ, whereas IL-10 production was unaffected.