Cytokine-induced changes in the leukon

Cytokines are regulatory peptides, produced by virtually every nucleated cell type in the body, that have pleiotropic effects on hematopoietic, lymphoid, and other cell types. Cytokines usually act locally as autocrine or paracrine cellular signals intended to maintain local homeostasis but in disease states can spill over into the circulation to initiate systemic reactions. The systemic administration of high doses of recombinant cytokines is associated with a multitude of pharmacologic and toxicologic effects, frequently involving the hemolymphopoietic system. These effects may represent direct or indirect pharmacologic or hyperpharmacologic activity or may represent toxicity. The objective of this review is to present the general types of hemolymphopoietic changes associated with cytokine administration to animals and to provide examples of cytokine-induced effects on the hemolymphopoietic system.