A contributing factor to the difficulty of distinguishing cytokines from hormones is that some immunomodulating effects of cytokines are systemic (i.e., affecting the whole organism) rather than local. For instance, to accurately utilize hormone terminology, cytokines may be autocrine or paracrine in nature, and chemotaxis, chemokinesis and endocrine as a pyrogen. Essentially, cytokines are not limited to their immunomodulatory status as molecules. alt=A scalable vector graphic of signal transduction pathways|thumb|Cytokines typically activate second messenger systems, like JAK-STAT pathways, as illustrated on the left side of the diagram. Conversely, hormones typically activate different signaling pathways, like G protein-coupled receptors, seen at the top of the figure.
A contributing factor to the difficulty of distinguishing cytokines from hormones is that some immunomodulating effects of cytokines are systemic (i.e., affecting the whole organism) rather than local. For instance, to accurately utilize hormone terminology, cytokines may be autocrine or paracrine in nature, and chemotaxis, chemokinesis and endocrine as a pyrogen. Essentially, cytokines are not limited to their immunomodulatory status as molecules. alt=A scalable vector graphic of signal transduction pathways|thumb|Cytokines typically activate second messenger systems, like JAK-STAT pathways, as illustrated on the left side of the diagram Conversely, hormones typically activate different signaling pathways, like G protein-coupled receptors, seen at the top of the figure.