ABSTRACT
Cytokines can be released into the systemic circulation and function in an endocrine fashion by the action of the macrophage and polymorphonuclear adherence to the endothelium or by the release of cytokines from the endothelial tissue itself. Cytokines differ from endocrine hormones in that they are produced from many cell types and typically influence tissues locally in a paracrine fashion at a lower concentration than hormones. Cytokines, and in particular tumor necrosis factor (TNF) and interleukin-1 (IL-1), induce major disruptions of normal lipid metabolism. Hypertriglyceridemia is present in many infected patients, including those with Human Immunodeficiency Virus (HIV), and is a symptom of the derangement of lipid metabolism. HIV-positive patients with secondary infections systematically had higher TNF concentrations than those without. The prevalence of elevated TNF levels was positively correlated with the progression of disease. Daily treatments with TNF eventually caused the rats to become resistant to the hemorrhagic effects of TNF, but the delayed gastric emptying persisted.
