TNF and serum lipopolysaccharide activity: Data from the present study, in concert with those from a previous report [19], confirm that endotoxemia induced by Gram (-) endotoxin i.p. administration can cause significant systemic inflammation within 24 h after administration, as our data demonstrate significant upregulation of the early response inflammatory cytokines TNF-α, IL-1β, and IL-6 in plasma.